TABLE 5

Overview of enzymes involved in pentose biosynthesis in Archaea, Bacteria, and Eukarya

EnzymeEC no.AbbreviationReactionProtein superfamily(ies) (according to SCOP)Protein family(ies)Distribution
Phosphohexulose isomerase5.3.1.27PHIFructose 6-phosphate ⇆ d-arabino-3-hexulose 6-phosphateSIS domain superfamilyMono-SIS domain familyArchaea (except for some halophiles and Thermoplasmatales), Bacteria (especially methylotrophs)
Hexulose phosphate synthase4.1.2.43HPSd-Arabino-3-hexulose 6-phosphate ⇆ ribulose 5-phosphate + formaldehydeRibulose phosphate binding barrel superfamilyArchaea (except for some halophiles and Thermoplasmatales), Bacteria (especially methylotrophs)
Ribose-5-phosphate isomerase5.3.1.6RPIRibulose 5-phosphate ⇆ ribose 5-phosphateNagB/RpiA/CoA transferase-like superfamily, ribulose 5-phosphate isomerase lid domain superfamilyd-Ribose-5-phosphate isomerase (RpiA), catalytic domain family; ribulose-5-phosphate isomerase lid domain familyArchaea, Bacteria, Eukarya
Transketolase2.2.1.1TKSedoheptulose 7-phosphate + d-glyceraldehyde-3-phosphate ⇆ d-ribose 5-phosphate + d-xylulose 5-phosphateThiamine diphosphate binding fold (THDP binding), TK C-terminal domain-likeTK-like Pyr module, transketolase C-terminal domain-likeMca. jannaschii, Thermoplasmatales, Thermococcales, Sulfolobales, Thermoproteales (not in most haloarchaea, other methanogens, and Archaeoglobales), Bacteria, Eukarya
Transaldolase2.2.1.2TASedoheptulose 7-phosphate + d-glyceraldehyde 3-phosphate ⇆ d-erythrose 4-phosphate + d-fructose 6-phosphateAldolase superfamilyClass I aldolase familyMethanococcus spp., Thermoplasmatales (not in most other Archaea), Bacteria, Eukarya
Glucose 6-phosphate dehydrogenase1.1.1.49G6PDHd-Glucose 6-phosphate + NAD(P)+d-glucono-1,5-lactone 6-phosphate + NAD(P)H + H+N-terminal domain NAD(P) binding Rossman fold-like domain superfamily; C-terminal glyceraldehyde-3-phosphate dehydrogenase-like, C-terminal domain superfamilyGAPDH N-terminal domain family, glucose-6-phosphate dehydrogenase-like family (C-terminal domain)Bacteria, Eukarya, some Haloarchaea
6-Phosphogluconate dehydrogenase1.1.1.446PGDH6-Phospho-d-gluconate + NADP+d-ribulose 5-phosphate + CO2 + NADPH + H+NAD(P) binding Rossman fold domains, 6-phosphogluconate dehydrogenase C-terminal domain-like superfamily6-Phosphogluconate dehydrogenase-like, N-terminal domain family; hydroxyisobutyrate and 6-phosphogluconate dehydrogenase domain familyBacteria, Eukarya
Ribose 5-phosphate epimerase5.1.3.1RPEd-Ribulose 5-phosphate ⇆ d-xylulose 5-phosphateRibulose phosphate binding barrel superfamilyd-Ribulose-5-phosphate 3-epimerase familyMethanococcus spp., Thermoplasmatales (not in most other Archaea), Bacteria, Eukarya