Protein Family Models

This domain is found in fungi, plants, archaea and bacteria. (from Pfam)

Date:

2024-08-14

Bacterial sulfur metabolism depends on the iron-containing porphinoid sirohaem. CysG, S-adenosyl-L-methionine (SAM)-dependent bis-methyltransferase, dehydrogenase and ferrochelatase, synthesises sirohaem from uroporphyrinogen III via reactions which encompass two branchpoint intermediates in tetrapyrrole biosynthesis, diverting flux first from protoporphyrin IX biosynthesis and then from cobalamin (vitamin B12) biosynthesis. CysG is a dimer of two structurally similar protomers held together asymmetrically through a number of salt-bridges across complementary residues in the CysG_dimeriser region to produce a series of active sites, accounting for CysG's multifunctionality, catalysing four diverse reactions: two SAM-dependent methylations, NAD+-dependent tetrapyrrole dehydrogenation and metal chelation. The CysG_dimeriser region holding the two protomers together is of 74 residues [1]. [1]. 14595395. CysG structure reveals tetrapyrrole-binding features and novel regulation of siroheme biosynthesis. Stroupe ME, Leech HK, Daniels DS, Warren MJ, Getzoff ED;. Nat Struct Biol. 2003;10:1064-1073. (from Pfam)

Date:

2024-10-16

bifunctional precorrin-2 dehydrogenase/sirohydrochlorin ferrochelatase catalyzes the dehydrogenation of precorrin-2 to form sirohydrochlorin, a precursor in both siroheme and adenosylcobalamin biosynthesis, as well as the subsequent ferrochelation of sirohydrochlorin to siroheme

Date:

2017-10-27

This HMM represents a subfamily of CysG N-terminal region-related sequences. All sequences in the seed alignment for this model are N-terminal regions of known or predicted siroheme synthases. The C-terminal region of each is uroporphyrin-III C-methyltransferase (EC 2.1.1.107), which catalyzes the first step committed to the biosynthesis of either siroheme or cobalamin (vitamin B12) rather than protoheme (heme). The region represented by this model completes the process of oxidation and iron insertion to yield siroheme. Siroheme is a cofactor for nitrite and sulfite reductases, so siroheme synthase is CysG of cysteine biosynthesis in some organisms.

Date:

2021-04-27