AC PIRSF000190 IP IPR000659 ID Pyd_amn-ph_oxd DE Pyridoxamine-phosphate oxidase TP Family AT REVIEWED+UNCHANGED

Most members of this group are FMN-dependent pyridoxamine oxidases () that catalyse the oxidation of pyridoxamine-5'-phosphate to pyridoxal-5-phosphate (PLP) and ammonia (the second step in the formation of the principle operating coenzyme PLP). However, a subgroup of this family, the phenazine biosynthesis enzyme PhzG (), is predicted to catalyse the final oxidation/aromatization reaction [PMID:15449932].

The enzyme from rabbit liver is a noncovalently linked homodimer with blocked amino termini [PMID:10024608].

For additional information please see [PMID:15502343].

// AC PIRSF036426 IP IPR012409 ID Sirohaem_synth DE Sirohaem synthase TP Family AT REVIEWED+UNCHANGED

Siroheme synthase (CysG), a multifunctional enzyme of the sirohaem and cobalamin (vitamin B12) biosynthesis pathways, represents a fusion between uroporphyrin-III C-methyltransferase (SUMT) and precorrin-2 oxidase/chelatase. Therefore, in some bacteria, all four reactions of sirohaem biosynthesis are catalysed by one multifunctional enzyme, sirohaem synthase [PMID:8243665].

Siroheme and cobalamin are related macrocyclic structures derived from uroporphyrinogen III by C-methylation of the tetrapyrrole framework. All biologically important modified tetrapyrroles (including also haem and chlorophyll) share a common biosynthetic pathway up to the synthesis of the first macrocyclic intermediate, uroporphyrinogen III [PMID:12196148]. Then, SUMT (corresponding to the C-terminal (CysGA) domain of CysG [PMID:7945210]) catalyses C-methylation of uroporphyrinogen III (). It transfers two methyl groups from S-adenosyl-L-methionine to the C-2 and C-7 atoms of uroporphyrinogen III to yield precorrin-2 via the intermediate formation of precorrin-1. SUMT is the first enzyme committed to the biosynthesis of either sirohaem or cobalamin rather than heme, and precorrin-2 is the last common intermediate in the biosynthesis of corrinoids such as cobalamin, sirohaem and coenzyme F430 [PMID:12196148]. SUMT belongs to the domain superfamily of tetrapyrrole (corrin/porphyrin) methylases (), which includes methylases that use S-AdoMet in the methylation of diverse substrates. A number of other methylases in the cobalamin biosynthesis pathway also belong to this domain superfamily. Stand-alone forms of SUMT are in and , and bifunctional uroporphyrin-III methyltransferase/uroporphyrinogen-III synthases are in .

In sirohaem biosynthesis, the next two steps are beta-NAD(+)-dependent dehydrogenation of precorrin-2 to generate sirohydrochlorin followed by ferrochelation to yield sirohaem [PMID:10051442, PMID:9461500]. Both of these steps are performed by precorrin-2 oxidase/ferrochelatase. In sirohaem synthase CysG, it corresponds to the N-terminal (CysGB) domain [PMID:10051442, PMID:9461500]. Stand-alone forms of precorrin-2 oxidase/ferrochelatase are in . Ferrochelation can also be performed by CbiK () [PMID:9150215] or by SirB [PMID:12408752] or CbiX [PMID:12686546] ().

In the anaerobic cobalamin biosynthesis (e.g., in Salmonella typhimurium), a cobaltochelatase produces cobalt-precorrin-2. This cobaltochelation can be performed by CbiK [PMID:9150215] or by CbiX [PMID:12917443, PMID:12686546], but also by CysGB homologues [PMID:8955319], even though this is not their primary function [PMID:9461500]. Therefore, CysGB can essentially duplicate the function of an unrelated chelatase, CbiK [PMID:8955319, PMID:9150215]. Note that in the aerobic cobalamin biosynthesis, cobalt insertion occurs in a later, different step (see ).

Precorrin-2 oxidase/chelatases, represented by the N-terminal domain of and by , are not similar in sequence or structural fold to any other known chelatases or oxidases [PMID:11980703, PMID:10051442]. Analysis of mutant proteins suggests that both catalytic activities share a single active site cleft formed between the N-terminal NAD-binding subdomain and the central subdomain [PMID:11980703]. Therefore, they can be considered as the third class of cobalt chelatases, in addition to class I (ATP-dependent, aerobic pathway ) and class II (ATP-independent, anaerobic pathway ) [PMID:12686546, PMID:8905078]. As with the class II chelatases, they do not require ATP for activity. However, they are not structurally similar to class II chelatases, and it is likely that they have arisen by the acquisition of a chelatase function within a dehydrogenase catalytic framework [PMID:11980703, PMID:12686546].

// AC PIRSF000099 IP ID Histidinol_dh DE Histidinol dehydrogenase TP Family AT AUTO+UNCHANGED

This group represents a histidinol dehydrogenase.

// AC PIRSF000105 IP IPR012131 ID HCDH DE 3-hydroxyacyl-CoA dehydrogenase TP Family AT AUTO+NEW

This group represents a 3-hydroxyacyl-CoA dehydrogenase.

// AC PIRSF000106 IP IPR001891 ID ME DE Malic enzyme TP Family AT AUTO+UNCHANGED

This group represents a malic enzyme.

// AC PIRSF000124 IP IPR014360 ID UDPglc_GDPman_dh DE UDP-glucose/GDP-mannose dehydrogenase TP Family AT AUTO+UNCHANGED

This group represents an UDP-glucose/GDP-mannose dehydrogenase.

// AC PIRSF000398 IP IPR012263 ID M_m6A_EcoRV DE Modification methylase (adenine-specific), M.EcoRV type TP Family AT AUTO+UNCHANGED

This group represents a modification methylase (adenine-specific), M.EcoRV type.

// AC PIRSF000724 IP IPR001576 ID Pgk DE Phosphoglycerate kinase TP Family AT AUTO+UNCHANGED

This group represents a phosphoglycerate kinase.

// AC PIRSF036497 IP ID HDH_short DE Homoserine dehydrogenase lacking ACT domain TP Family AT AUTO+NEW

This group represents a homoserine dehydrogenase lacking ACT domain.

// APPENDIX - PMIDs: PMID:10024608 PMID:15449932 PMID:15502343 PMID:12196148 PMID:10051442 PMID:8243665 PMID:8905078 PMID:12686546 PMID:9150215 PMID:8955319 PMID:9461500 PMID:7945210 PMID:11980703 PMID:12408752 PMID:12917443 // APPENDIX - DOMAIN ARCHITECTURE PIRSF000099 (509 full members) contains PF00815(440) PIRSF000105 (726 full members) contains PF00725(681), PF02737(682) PIRSF000106 (641 full members) contains PF00390(580), PF03949(579) PIRSF000124 (1044 full members) contains PF00984(921), PF03720(907), PF03721(920) PIRSF000190 (342 full members) contains PF01243(308) PIRSF000398 (289 full members) contains PF02086(262) PIRSF000724 (791 full members) contains PF00162(721) PIRSF036426 (173 full members) contains PF00590(158) PIRSF036497 (102 full members) contains PF00742(91), PF03447(85) // APPENDIX - RELATIONSHIPS // APPENDIX - REVISIONS //