We will pay considerable attention to the involvement of glucosephosphate dehydrogenase, the rate-limiting enzyme of the PPP. Subsequently, we discuss the inhibition of the PPP as a potential therapeutic strategy against cancer, in particular, HCC. Over the past 20 years, there has been a growing interest in tumor metabolism and, in particular, glucose metabolism.
Thus, reprogramming of energy metabolism by tumor cells has now been acknowledged as one of the crucial hallmarks of cancer 1 , 2. These metabolic alterations constitute a selective advantage for tumor growth, proliferation, and survival as they provide support to the crucial needs of tumor cells, such as increased energy production, macromolecular biosynthesis, and maintenance of redox balance 7 — 9.
In this regard, it should be underlined that altered glucose metabolism involves not only glycolysis but also other metabolic pathways requiring glucose utilization, such as the pentose phosphate pathway PPP , one of the pivotal components of cell metabolism. The PPP has gained recognition as it helps tumor cells to satisfy their anabolic demands and maintains the redox homeostasis of cells. This review will summarize the observations regarding the involvement of the PPP in cancer, in particular the role of glucosephosphate dehydrogenase G6PD and its relevance for possible therapeutic approaches.
The PPP, also known as phosphogluconate pathway or the hexose monophosphate shunt, branches from glycolysis as the first committed step of glucose metabolism, which is catalyzed by hexokinases phosphorylating glucose, in order to generate glucosephosphate G6P. This reaction is considered to be the most relevant step in glucose metabolism as G6P is at the convergence point of glycolysis, PPP, hexosamine synthesis pathway, and glycogen synthesis 2 , The PPP is composed of two functionally interrelated branches: the oxidative and the non-oxidative.
This product is next hydrolyzed by phosphogluconolactonase to generate 6-phosphogluconate. The next generation of ribosephosphate from Ru5P and its conversion to phosphoribosyl pyrophosphate provides the backbone for the synthesis of ribonucleotides 10 — The non-oxidative arm of the PPP generates pentose phosphates for ribonucleotide synthesis in a series of reversible reactions that produce also other metabolites, such as fructosephosphate F6P and glyceraldehydephosphate G3P The generation of pentose phosphates to ensure elevated nucleic acid synthesis and NADPH production make the PPP pathway particularly critical for tumor cells.
PPP activation has been widely demonstrated in different types of cancer and associated with invasion, metastasis, angiogenesis, and response to chemotherapy and radiotherapy 15 , Moreover, accumulating data have reported upregulation of several enzymes of both oxidative and non-oxidative branches of the PPP in tumor cells. This section will provide a summary of these observations. Initial studies on G6PD, the rate-limiting enzyme of the oxidative arm of the PPP, mostly focused on erythrocytes, as individuals susceptible to hemolytic anemia show genetically inherited G6PD-reduced activity 18 , Following these observations, it was found that G6PD is highly conserved in most mammalian species 20 and is present in many normal tissues, such as mammary and adrenal glands, adipose tissue, spleen, lung, liver, and neuronal cells 21 — Moreover, hepatic G6PD is also regulated by nutritional signals, including a high-carbohydrate diet, polyunsaturated fatty acids, and hormones, such as insulin and glucocorticoids 20 , Numerous studies have revealed a significant upregulation of G6PD in tumor cells and neoplastic tissues Table 1.
First of all, Board et al. Later on, analysis of intracellular G6PD activity in various cancer cell lines, such as human cervical carcinomas, esophageal carcinomas, hepatomas, lung adenocarcinomas, and colon adenocarcinomas, revealed that G6PD was particularly overexpressed in human esophageal cancer cell lines In the same study, it was shown that following transfection of NIH 3T3 fibroblasts with human G6PD cDNA, G6PD-overexpressing cells were not contact inhibited, displayed anchorage-independent growth in soft agar, and divided more quickly.
In nude mice, G6PD-overexpressing cells gave rise to rapidly growing, large fibrosarcomas, characterized by the abundance of new blood vessels, therefore suggesting angiogenic properties of high levels of G6PD In animal models of carcinogenesis, increased G6PD activity was observed in estrogen-induced kidney tumors in Syrian hamsters when compared to untreated controls Using a histochemical technique, an increased G6PD activity was reported in human cervical cancer and colon carcinoma 32 , Elevated G6PD activity in cervical intraepithelial neoplasia, as well as in endometrial carcinoma, was further confirmed in different studies 34 — 36 ; G6PD activity was also significantly higher in human colon cancer specimens when compared with normal epithelium and in chemically induced mice colon carcinomas On the other hand, a very weak G6PD activity was observed in lung cancer 33 , and variable results were obtained in breast carcinoma cells 41 , However, a recent study by Rao et al.
Furthermore, G6PD glycosylation was shown to promote cancer cell proliferation in vitro and tumor growth in vivo Not only increased G6PD activity was found in prostatic carcinoma when compared to benign hyperplasia but a positive correlation between its enzymatic activity and differentiation degree as well as clinical stage was observed In this study, delayed formation and reduced growth of tumor cells in nude mice injected with AG6PD-deficient cells were also demonstrated In gastric cancer, Kekec et al.
Moreover, Wang et al. Overall, these results suggest that G6PD overexpression may represent an independent predictor of poor prognosis for patients with gastric cancer. Table 1. Glucosephosphate dehydrogenase G6PD overexpression in different tumor types. Although the non-oxidative arm of the PPP has been underrated for a long time, an increasing amount of experimental evidence suggests its importance in cancer cell metabolism.
In normal tissues, while the highest TALDO activities have been reported in thymus and intestinal mucosa, the highest TKT activity has been observed in kidney, intestinal mucosa, thymus, and liver Finally, the relevance of human TALDO has been recognized not only for its involvement in cancer but also in different autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis Hanczko et al. Coy et al.
Nonetheless, the contribution of TKTL1 in tumor cell metabolism has been demonstrated by the finding that inhibition of TKTL1 in different tumor cells caused a significantly decrease in cell proliferation 58 , While overexpression of mutated TKTL1 has been reported in urothelial and colorectal cancer and correlated with tumor invasiveness as well as predicted poor patient outcome, TKT and TKTL2 expression were not altered in this study A significant association was also found between TKTL1 protein expression and the presence of multifocality, extra-thyroidal extension, vascular invasion, and lymph-node metastases Noteworthy, similar results were also observed in gastric 63 and renal cancer 40 , nasopharyngeal carcinoma 64 , glioblastoma multiforme 65 , and head and neck squamous cell carcinoma patients 66 , implicating TKTL1 as a novel candidate oncogene 15 , TKT expression was positively associated with aggressive clinicopathological HCC features presence of venous invasion, increased tumor size, absence of tumor encapsulation.
Accordingly, the use of TKT inhibitor oxythiamine OT significantly sensitized human HCC cells to sorafenib treatment in vitro and suppressed tumor growth in vivo These results, together with those stemming from the analysis of TALDO, suggest that the role of non-oxidative branch of PPP in HCC may not be the same as that of other tumors, and its full understanding requires further investigation.
This tumor is characterized by a poor patient outcome due to limited therapeutic options 67 , and it has been acknowledged as a typical example of glucose metabolism reprogramming in cancer cells 2. In rat experimental models consisting of normal and regenerating livers and cell lines, G6PD activity was found to be highly increased in the Novikoff hepatoma 68 and in eight rapidly growing hepatomas, but not in the one displaying a slow growth rate An increase in G6PD-positivity in preneoplastic hepatic lesions and HCC, associated with a high labeling index, has been also reported in different studies using a rat protocol of hepatocarcinogenesis induced by N -nitrosomorpholine 70 — Later on, Frederiks et al.
Moreover, the same study reported that G6PD silencing significantly inhibited HepG2 cell line invasion. In line with these observations, our recent data obtained from two different cohorts of patients who have undergone liver resection for HCC or liver biopsies demonstrated a significant G6PD upregulation in most of the tumors when compared to their peri-tumoral counterpart Remarkably, such increase in G6PD expression was significantly associated with high-grade HCCs, and positively correlated with metastasis formation and decreased overall survival.
The increased expression of G6PD appeared to be a general phenomenon, as stratification of patients according to their etiology did not reveal any significant association with the mRNA levels of the enzyme The clinical importance of these data resulted also from the observation that lower expression of G6PD in patients who received sorafenib treatment after liver cancer surgery was significantly associated with better progression-free and overall survival.
In fact, both G6PD and 6PGD have been shown to be increased in cervical carcinoma 32 , 34 , 36 , as well as in lung tumors The critical role of 6PGD in cancer cell proliferation has been described in non-small cell lung carcinoma. An increased activity of 6PGD was also reported in rat hepatic preneoplastic lesions induced by DENA or by the R-H model when compared with the surrounding parenchyma 73 — Pentose phosphate pathway activation has been suggested as a mechanism by which dysregulated NRF2—KEAP1 signaling promotes cellular proliferation and tumorigenesis Transcription factor NRF2 [NFE2L2, nuclear factor erythroid-derived-2 -like 2] is known as a major sensor of oxidative stress in the cell.
Exposure to electrophiles or ROS causes modification of the cysteine residues of Keap1, leading to its inactivation. Hence, NRF2 becomes stabilized and translocates to the nucleus, where it induces transcription of numerous antioxidant and detoxifying genes by binding to the antioxidant response elements in their regulatory regions 84 , The induction of these genes confers resistance against xenobiotic and oxidative stress.
However, it should be underlined that the genes involved in the antioxidant response are not the only group of NRF2 target genes with possible relevance to cancer development. HBx was shown to interact with p62 and Keap1 to generate HBx—p62—Keap1 aggregates in the cytoplasm, leading to the Nrf2 nuclear translocation and its activation Moreover, we have recently shown 76 that G6PD upregulation occurred only in the highly proliferating aggressive cytokeratin positive KRT rat preneoplastic hepatic nodules, characterized by activation of the NRF2—KEAP1 pathway, but not in slow-growing lesions Figure 1.
Figure 1. Glucosephosphate dehydrogenase G6PD , 6-phosphogluconate dehydrogenase, transketolase, and transaldolase modifications in normal regenerating liver following partial hepatectomy A , preneoplastic lesions endowed with different aggressive behavior B,C , and hepatocellular carcinoma HCC D.
Red color indicates positive staining for G6PD. Thickness of the arrows represents the magnitude of G6PD expression. Recently, it has been proposed that NRF2 may coordinate the regulation of metabolic genes. The control of gene expression by miRNAs—small, evolutionarily conserved, non-coding RNAs—has been frequently observed in a wide range of human pathologies, including cancer It has been proposed that the metabolism of highly dividing cells, either normal or neoplastic cells, is adapted to facilitate the uptake and incorporation of nutrients into the biomass e.
Since pentoses are required for DNA synthesis, it is not surprising that metabolic changes leading to increased G6PD expression occur in different cancers, including HCC. However, it is unclear whether the induction of the oxidative arm of PPP is required for the proliferation of normal cells.
This is a crucial point to be addressed, since, ideally, therapeutic drugs directed against specific molecules should not harm normal cells. The liver is a perfect organ to address this question. Indeed, although adult liver is normally a quiescent organ, it is characterized by a rapid and highly synchronous proliferative activity in response to a reduction in liver mass caused by different stimuli physical, chemical, nutritional, vascular, or virus-induced liver injury. Following the removal of two-thirds of the liver, the residual lobes enlarge to restore the original liver mass and the whole process, in rats and mice, is completed within 5—7 days after surgery Intriguingly, Heinrich et al.
Later on, other studies demonstrated that also the oxidative branch does not seem to be involved. Indeed, Weber and Cantero 68 observed that G6PD activity in rats undergoing PH and in sham-operated animals did not differ significantly. Moreover, it was reported that both G6PD and 6PGD activities were even lower 48 h after PH, in particular in intermediate and pericentral zones, when compared with the activity observed in control liver In accordance with these results, a recently performed comparison of samples obtained 24 and 48 h after PH time of maximal DNA synthesis and of the second peak of hepatocyte proliferation, respectively with quiescent liver, demonstrated that G6PD mRNA and protein levels and its activity were found profoundly downregulated in regenerating liver following PH Although the reason underlying this apparently paradoxical effect is unknown, two possible explanations can be offered: i enhanced expression of G6PD is specific for cells destined to cancer progression, while liver regeneration can be sustained by pentoses generated by the non-oxidative PPP in a G6PD-independent manner, or by others sources.
As recognized 2 , 91 , the balance between oxidative branch and non-oxidative branch of the PPP depends on the redox and metabolic status of the cell. Thus, it is likely that the primary role of oxidative PPP induction is to maintain the redox equilibrium in pre- or neoplastic hepatocytes characterized by high intracellular ROS levels, compared to the non-tumorigenic counterpart 10 , In this context, it is worth to mention that suppression of glycolysis by TIGAR which enabled a reduction of intracellular ROS, via increased PPP activity, has been reported in several cell lines 97 and in KRTpositive preneoplastic liver nodules 76 ; ii PPP is downregulated in regenerating liver to enable glycolysis, since energy production and biomass formation are the most important needs for the metabolic readjustment of the residual liver post-surgery Overall, the results obtained in distinct experimental models preneoplastic vs.
Intriguingly, G6PD expression appears to discriminate the most aggressive preneoplastic lesions from those that most likely undergo spontaneous regression 76 Figure 1. In this context, it would be interesting to see whether G6PD expression might also be used to differentiate human dysplastic nodules with different growth capacity.
Given the important role of the PPP in cancer metabolism, it is not surprising that targeting the PPP with selective and specific modulators has been widely considered as a relevant and challenging therapeutic option 98 , However, at present, only few PPP inhibitors are available, and their clinical use has been considered limited see Table 2.
Among them, there is an uncompetitive G6PD inhibitor, dehydroepiandrosterone DHEA which together with its sulfate form, represents the most abundant circulating steroid hormone in humans and is the major secreted product of the adrenal glands , The molecular basis of this inhibition seems to be due to the binding of DHEA to the ternary enzyme—coenzyme—substrate ternary complex es Administration of DHEA was able to inhibit the growth of early preneoplastic liver lesions and delay the progression to HCC of persistent liver nodules induced by the R-H model , In vitro studies by Tian et al.
However, more recently, it was proposed that the anti-tumorigenic effects of DHEA might not be due to G6PD inhibition, but rather to the malfunctioning of mitochondria and the consequent cessation of cell growth This finding, together with the adverse side effects emerged in rodents after a long-term DHEA treatment , led to the use of DHEA analogs, which are more potent inhibitors of G6PD than the parent compound and do not cause major side effects , Further studies have suggested that response to radiotherapy might depend on the activity of the PPP , Indeed, the combined treatment of 6-AN and radiation achieved a higher percentage of tumor growth delay than either 6-AN or radiotherapy alone in mouse mammary carcinoma tumor model In agreement with the observations that changes in PPP activity may also influence the response of tumor cells to chemotherapy, it has been reported that both DHEA and 6-AN not only were able to reverse the increase of G6PD and GSH but also inhibited multidrug resistance in the doxorubicin-resistant human colon cancer cell line HTDX.
These results suggest that G6PD inhibition may sensitize drug-resistant cancer cells to the cytotoxic effect of doxorubicin Furthermore, colony-forming assays demonstrated that pretreatment with 6-AN resulted in increased sensitivity to the cytotoxic effects of cisplatin in a variety human tumor cell lines Unfortunately, the clinical use of 6-AN is hampered by its toxicity at high concentrations and its severe side effects, such as B-complex vitamin deficiency and a serious neurologic damage , A high-throughput screening approach performed to identify novel human G6PD inhibitors, selected few compounds that were even to 1,fold more potent when compared with DHEA or 6-AN.
Some natural products, such as gallated catechins or rosmarinic acid, have been also proposed as G6PD inhibitors , With regard to the non-specific inhibitors, it has been reported that treatment with Imatinib Gleevec , a tyrosine kinase inhibitor designed to specifically target the BCR-ABL oncogene protein, was able to decrease the activity of both hexokinase and G6PD in leukemia cells, leading to suppression of aerobic glycolysis , In this group of compounds, also genistein, the isoflavonoid of the soy plant, was able to decrease G6PD and the activity of the pentose cycle in MIA pancreatic adenocarcinoma cells Unfortunately, the paucity of studies aimed at investigating the effect of G6PD inhibitors on HCC development is not sufficient to draw any possible conclusion on their efficacy.
Nevertheless, the emerging evidence that increased hepatocyte G6PD expression is a feature unique to the tumorigenic process makes the search for reliable G6PD inhibitors a very attractive and stimulating topic. Indeed, the decreased NADPH generation following the treatment with inhibitors of the oxidative PPP i could represent a condition sufficient to selectively eradicate cancer cells by decreasing the resistance of pre- and neoplastic hepatocytes to intracellular ROS and ii might increase, in conjunction with already-approved therapy [i.
Oxidative PPP activation can help transformed cells to escape oxidative stress by increasing the intracellular redox power of cancer cells through enhanced NADPH production. It is thus obvious that we can look at the enzymes involved in this pathway as potential pharmacological targets. However, although significant evidence suggest that PPP enzymes might represent reliable prognostic markers in different tumor types, not sufficient efforts have been undertaken to establish the role of the enzymes involved in the PPP in cancer.
Moreover, the therapeutic potential hidden in this metabolic pathway is strongly limited by the lack of specific pharmacological inhibitors, as so far specific and effective inhibitors are unavailable. Indeed, the recent observation that anti-proliferative effects of DHEA are most likely not due to G6PD inhibition but rather to changes in mitochondrial gene expression highlights the need for novel selective G6PD inhibitors to investigate the impact of this enzyme on human diseases.
Nevertheless, the emerging evidence that increased hepatocyte G6PD expression as a feature unique to the tumorigenic process makes the search for reliable G6PD inhibitors very attractive in the field of HCC. Indeed, the decreased NADPH generation following the treatment with inhibitors of the oxidative PPP, i could represent a condition sufficient to selectively eradicate cancer cells by decreasing their resistance to high intracellular ROS levels; ii might increase, in conjunction with already-approved therapy [i.
The design of specific inhibitors targeting PPP is thus highly desirable as they might represent a useful therapeutic tool, in particular, for HCC. In conclusion, the growing interest in metabolic reprogramming of cancer cells and the emerging evidence of the association between activation of oxidative PPP and tumor aggressiveness will hopefully fuel innovative approaches to unveil the role of this pathway in cancer therapy. MK, AC, and AP were equally responsible for the conception, design, and drafting of the article and final approval. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
The authors apologize to all colleagues whose work could not be cited owing to space restrictions. MK: recipient of a Fondazione Umberto Veronesi fellowship. Hanahan D, Weinberg RA. Hallmarks of cancer: the next generation. Cell — Hay N. Reprogramming glucose metabolism in cancer: can it be exploited for cancer therapy?
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Mol Cell Biochem —5. H11R3 Laribacter hongkongensis Pseudogulbenkiania sp. NH8B Jeongeupia sp. USM3 Aquaspirillum sp. LM1 Aquitalea magnusonii Aquitalea sp. CCGE Burkholderia sp. YI23 Burkholderia sp. KJ Burkholderia insecticola Burkholderia sp. RPE67 Burkholderia sp.
Bp Burkholderia sp. OLGA Burkholderia sp. PAMC Burkholderia sp. CCGE Paraburkholderia phenoliruptrix Paraburkholderia phytofirmans Paraburkholderia fungorum Paraburkholderia caribensis Paraburkholderia sprentiae Paraburkholderia sp.
SOS3 Paraburkholderia aromaticivorans Paraburkholderia hospita Paraburkholderia terrae Paraburkholderia graminis Paraburkholderia caledonica Paraburkholderia terricola Paraburkholderia rhizoxinica Polynucleobacter asymbioticus Polynucleobacter necessarius Polynucleobacter duraquae Polynucleobacter paneuropaeus Pandoraea pnomenusa 3kgm Pandoraea pnomenusa RB38 Pandoraea pnomenusa DSM Pandoraea pnomenusa Pandoraea pulmonicola Pandoraea sputorum Pandoraea apista Pandoraea vervacti Pandoraea oxalativorans Pandoraea thiooxydans Pandoraea faecigallinarum Pandoraea norimbergensis Pandoraea sp.
XY-2 Paucimonas lemoignei Hydromonas sp. H Bordetella genomosp. HZ20 Bordetella sp. T Pusillimonas sp. H8 Kerstersia gyiorum Rhodoferax ferrireducens Rhodoferax saidenbachensis Rhodoferax antarcticus Rhodoferax koreense Polaromonas sp. JS Polaromonas naphthalenivorans Polaromonas sp. SP1 Acidovorax citrulli Acidovorax sp.
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SC Melaminivora sp. Pch-M Herminiimonas arsenicoxydans Janthinobacterium sp. Marseille Janthinobacterium agaricidamnosum Janthinobacterium sp. B Janthinobacterium sp. LM6 Janthinobacterium svalbardensis Janthinobacterium sp. NR Massilia sp. KCTC Mitsuaria sp. AL Nitrosomonas sp. Is79A3 Nitrosomonas communis Nitrosomonas ureae Nitrosospira multiformis Nitrosospira lacus Sulfuritalea hydrogenivorans Methyloversatilis sp.
RAC08 Thiobacillus denitrificans Methylobacillus flagellatus Methylotenera mobilis Methylotenera versatilis Methylovorus glucosetrophus Methylovorus sp. AH1 Ferriphaselus amnicola Aromatoleum aromaticum Azospira oryzae Rugosibacter aromaticivorans Rhodocyclaceae bacterium Thauera-like Dechloromonas aromatica Dechloromonas sp. HYN Azoarcus sp. BH72 Azoarcus sp. KH32C Azoarcus sp. CIB Azoarcus olearius Azoarcus sp. SY39 Azoarcus communis Azoarcus sp. DN11 Azoarcus sp. DD4 Thauera sp. RM Campylobacter subantarcticus LMG Campylobacter subantarcticus LMG Campylobacter gracilis Campylobacter ureolyticus Campylobacter hyointestinalis Campylobacter helveticus Campylobacter sputorum Campylobacter pinnipediorum Campylobacter cuniculorum Campylobacter lanienae Campylobacter avium Campylobacter hepaticus Campylobacter sp.
RM Campylobacter sp. L Arcobacter sp. LPB Sulfurospirillum deleyianum Sulfurospirillum barnesii Sulfurospirillum multivorans Sulfurospirillum halorespirans Sulfurospirillum sp. SL Sulfurospirillum sp. JPD-1 Hydrogenimonas sp. MAG Nitratifractor salsuginis Nitratiruptor sp. SB Sulfurovum sp.
M21 Geobacter sp. M18 Geobacter pickeringii Geobacter anodireducens Geoalkalibacter subterraneus Pelobacter carbinolicus Pelobacter propionicus Pelobacter acetylenicus Pelobacter sp. SFB93 Desulfuromonas soudanensis Desulfuromonas sp. Fw Anaeromyxobacter sp. K Myxococcus xanthus Myxococcus fulvus Myxococcus stipitatus Myxococcus hansupus Myxococcus macrosporus Corallococcus coralloides Stigmatella aurantiaca Archangium gephyra Melittangium boletus Cystobacter fuscus Vulgatibacter incomptus Sorangium cellulosum So ce56 Sorangium cellulosum So Chondromyces crocatus Sandaracinus amylolyticus Labilithrix luteola Minicystis rosea Haliangium ochraceum Syntrophus aciditrophicus Desulfobacca acetoxidans Desulfomonile tiedjei Syntrophobacter fumaroxidans Desulfoglaeba alkanexedens Desulfarculus baarsii Hippea maritima Desulfurella acetivorans Bradymonas sediminis Bdellovibrio bacteriovorus HD Bdellovibrio bacteriovorus Tiberius Bdellovibrio bacteriovorus W Bdellovibrio bacteriovorus J Bdellovibrio exovorus Bdellovibrio sp.
HF Neorickettsia sennetsu Neorickettsia risticii Neorickettsia helminthoeca Candidatus Midichloria mitochondrii Candidatus Fokinia solitaria Rickettsiales bacterium Ac37b Rickettsiales endosymbiont of Stachyamoeba lipophora Candidatus Paracaedibacter acanthamoebae Candidatus Paracaedimonas acanthamoebae Candidatus Nucleicultrix amoebiphila Endosymbiont of Acanthamoeba sp.
B7 Mesorhizobium sp. WSM Mesorhizobium sp. Pch-S Chelativorans sp. BNC1 Hoeflea sp. RAC02 Sinorhizobium americanum Sinorhizobium sp. H Agrobacterium sp. RAC06 Agrobacterium rhizogenes Agrobacterium sp. IE Rhizobium leguminosarum bv. N Rhizobium phaseoli Rhizobium sp. NT Rhizobium sp. N Rhizobium sp. S41 Rhizobium sp. Kim5 Rhizobium esperanzae Rhizobium jaguaris Rhizobium sp. SOG26 Neorhizobium sp. HZN7 Brucella melitensis bv. ORS Bradyrhizobium sp. BTAi1 Bradyrhizobium sp.
S Bradyrhizobium oligotrophicum Bradyrhizobium sp. BF49 Bradyrhizobium icense Bradyrhizobium sp. SK17 Bradyrhizobium ottawaense Bradyrhizobium sp. PAMC Bosea sp. RAC05 Bosea vaviloviae Bosea sp. JB15 Bartonella sp. AB Bartonella sp. Raccoon60 Bartonella sp. DM1 Methylobacterium sp. XJLW Methylobacterium sp. H Devosia sp. I Devosia sp. Gsoil Blastochloris viridis Blastochloris sp. GI Rhodoplanes sp. Z2-YC Maritalea myrionectae Methylocystis sp. SM30 Martelella endophytica Martelella sp.
AD-3 Martelella mediterranea Aureimonas sp. AU20 Breoghania sp. FWC26 Phenylobacterium zucineum Phenylobacterium sp. HYN Brevundimonas subvibrioides Brevundimonas sp. DS20 Brevundimonas naejangsanensis Brevundimonas sp. GWLB2 Brevundimonas sp. TM Ruegeria sp. NKC Ruegeria sp. AD91A Epibacterium mobile Rhodobacter sphaeroides 2.
LPB Rhodobacter blasticus Jannaschia sp. BM15 Paracoccus sp. SC Paracoccus sp. NJS Leisingera aquaemixtae Roseibacterium elongatum Planktomarina temperata Celeribacter indicus Celeribacter marinus Celeribacter ethanolicus Celeribacter manganoxidans Marinovum algicola Confluentimicrobium sp. MB Rhodovulum sp. P5 Pannonibacter phragmitetus Halocynthiibacter arcticus Labrenzia sp.
CP4 Labrenzia aggregata Labrenzia sp. VG12 Defluviimonas alba Yangia sp. AM1-D1 Sulfitobacter pseudonitzschiae Sulfitobacter sp. SK Sulfitobacter sp. JL08 Sulfitobacter sp. D7 Sulfitobacter donghicola Marivivens sp. P11 Thalassococcus sp. S3 Gemmobacter sp. HYN Tabrizicola sp. K13M18 Silicimonas algicola Sedimentitalea sp. W43 Haematobacter massiliensis Boseongicola sp. CCM32 Pseudorhodobacter sp. S12M18 Litoreibacter sp. P6W Novosphingobium sp. THN1 Novosphingobium tardaugens Novosphingobium sp. LPB Sphingopyxis sp. QXT Sphingopyxis sp. MG Uncultured Sphingopyxis sp.
LM7 Sphingomonas sp. LK11 Sphingomonas sp. JJ-A5 Sphingomonas sp. KC8 Sphingomonas sp. Cra20 Sphingomonas sp. SYK-6 Sphingobium sp. YBL2 Sphingobium baderi Sphingobium sp. MI Sphingobium sp. EP Sphingobium sp. RAC03 Sphingobium indicum Sphingobium sp. YG1 Citromicrobium sp. JL Sphingorhabdus sp. M41 Sphingorhabdus sp. SMR4y Sphingorhabdus sp. KY5 Erythrobacter sp. YH Altererythrobacter atlanticus Altererythrobacter marensis Altererythrobacter epoxidivorans Altererythrobacter namhicola Altererythrobacter dongtanensis Altererythrobacter sp.
B11 Croceicoccus naphthovorans Croceicoccus marinus Porphyrobacter neustonensis Porphyrobacter sp. LM 6 Porphyrobacter sp. Ha5 Swingsia samuiensis Swingsia sp. XM-1 Magnetospirillum sp. ME-1 Azospirillum sp. TSH58 Azospirillum sp. M2T2B2 Azospirillum sp. QH-2 Haematospirillum jordaniae Nitrospirillum amazonense Niveispirillum cyanobacteriorum Ferrovibrio sp. JS Bacillus sp. X1 Bacillus sp. WP8 Bacillus sp. Pc3 Bacillus sp. BH Bacillus sp.
OxB-1 Bacillus sp. YP1 Bacillus sp. BS34A Bacillus sp. LM Bacillus filamentosus Bacillus smithii Bacillus simplex Bacillus oceanisediminis Bacillus glycinifermentans Bacillus flexus Bacillus gibsonii Bacillus weihaiensis Bacillus xiamenensis Bacillus horikoshii Bacillus krulwichiae Bacillus beveridgei Bacillus kochii Bacillus altitudinis Bacillus sp. Y1 Oceanobacillus iheyensis Oceanobacillus sp. WCH70 Geobacillus sp. YMC61 Geobacillus sp. YMC52 Geobacillus sp. CT3 Geobacillus sp. GHH01 Geobacillus genomosp.
LC Geobacillus stearothermophilus Geobacillus subterraneus Geobacillus sp. B2M1 Anoxybacillus amylolyticus Anoxybacillus sp. B7M1 Amphibacillus xylanus Lysinibacillus sphaericus Lysinibacillus varians Lysinibacillus fusiformis Lysinibacillus sp. YS11 Lysinibacillus sp.
B2A1 Lysinibacillus sp. SK37 Virgibacillus halodenitrificans Virgibacillus sp. AT1b Exiguobacterium antarcticum Exiguobacterium sp. MH3 Exiguobacterium sp. U Gemella sp. JDR-2 Paenibacillus sp. FSL P Paenibacillus sp. FSL R Paenibacillus sp. FSL H Paenibacillus sp. XH2 Aneurinibacillus soli Cohnella sp. HS21 Saccharibacillus sp. ATSA2 Alicyclobacillus acidocaldarius subsp. R Planococcus sp. MB-3u Jeotgalibacillus malaysiensis Kurthia sp. P33 Sporosarcina sp.
P37 Sporosarcina ureae Sporosarcina sp. K2R Paenisporosarcina antarctica Planomicrobium glaciei Novibacillus thermophilus Laceyella sacchari Thermoactinomyces vulgaris Lactococcus lactis subsp. I-G2 Streptococcus sp. I-P16 Streptococcus sp. VT Streptococcus pantholopis Streptococcus sp. A12 Streptococcus sp. CF Vagococcus sp. MN Oenococcus oeni Oenococcus sp. C2 Leuconostoc carnosum Leuconostoc gelidum subsp. CP1 Carnobacterium divergens Marinilactibacillus sp.
Saccharomyces cerevisiae pentose phosphate pathway
PTS Jeotgalibaca dankookensis Jeotgalibaca sp. SY Clostridium sp. YL58 Ruminococcus torques Blautia hansenii Blautia sp. N6H Blautia producta Lachnoclostridium phytofermentans Lachnoclostridium sp. DCA Dehalobacter sp. CF Dehalobacter restrictus Heliobacterium modesticaldum Eubacterium eligens Eubacterium limosum Eubacterium maltosivorans Acetobacterium woodii Oscillibacter valericigenes Oscillospiraceae bacterium J Thermaerobacter marianensis Thermaerobacter sp.
X Thermoanaerobacter sp. SP Acetohalobium arabaticum Halobacteroides halobius Anoxybacter fermentans Finegoldia magna Anaerococcus prevotii Parvimonas micra Peptoniphilus sp. NBRC Spiroplasma sp. TU Candidatus Izimaplasma sp. JS Mycobacterium ulcerans Mycobacterium sp. MCS Mycobacterium sp. KMS Mycobacterium sp. EPa45 Mycobacterium haemophilum Mycobacterium sp.
ATCC Corynebacterium doosanense Corynebacterium humireducens Corynebacterium singulare Corynebacterium marinum Corynebacterium kutscheri Corynebacterium camporealensis Corynebacterium mustelae Corynebacterium epidermidicanis Corynebacterium testudinoris Corynebacterium uterequi Corynebacterium lactis Corynebacterium deserti Corynebacterium simulans Corynebacterium stationis Corynebacterium crudilactis Corynebacterium frankenforstense Corynebacterium phocae Corynebacterium flavescens Corynebacterium glaucum Corynebacterium striatum Corynebacterium aquilae Corynebacterium sphenisci Corynebacterium ammoniagenes Corynebacterium minutissimum Corynebacterium pelargi Brevibacterium flavum ZL-1 Nocardia farcinica IFM Nocardia farcinica NCTC Nocardia cyriacigeorgica Nocardia brasiliensis Nocardia nova Nocardia sp.
Y48 Nocardia seriolae Nocardia terpenica Nocardia sp. B Rhodococcus aetherivorans Rhodococcus fascians Rhodococcus sp. WMMA Rhodococcus sp. HY Streptomyces coelicolor Streptomyces albidoflavus Streptomyces avermitilis Streptomyces griseus Streptomyces globisporus Streptomyces scabiei Streptomyces sp. Mg1 Streptomyces sp. CFMR 7 Streptomyces sp. CdTB01 Streptomyces reticuli Streptomyces sp. SAT1 Streptomyces clavuligerus Streptomyces griseochromogenes Streptomyces qaidamensis Streptomyces lincolnensis Streptomyces noursei Streptomyces pluripotens Streptomyces sp.
CGR1 Microbacterium sp. XT11 Microbacterium sp. BH Microbacterium sp. BH Curtobacterium sp. SGAir Microterricola viridarii Frondihabitans sp. MFA Agromyces sp. FWM-8 Cryobacterium arcticum Cryobacterium sp. LW Cnuibacter physcomitrellae Aurantimicrobium minutum Aurantimicrobium sp. MWH-Mo1 Aurantimicrobium sp.
CGMCC 1. UTAS Humibacter sp. BT Humibacter sp. WJ Gryllotalpicola sp. PAX8 Leucobacter sp. DSM Leucobacter triazinivorans Agrococcus sp. SGAir Arthrobacter sp. FB24 Arthrobacter sp. Rue61a Arthrobacter sp. PAMC Arthrobacter sp. LS16 Arthrobacter sp.