3DFZ

SirC, precorrin-2 dehydrogenase

3DFZ の概要

• エントリーDOI: 10.2210/pdb3dfz/pdb
• 分子名称: Precorrin-2 dehydrogenase, SULFATE ION, GLYCEROL, ... (4 entities in total)
• 機能のキーワード: nad dehydrogenase, cobalamin biosynthesis, nad, oxidoreductase, porphyrin biosynthesis
• 由来する生物種: Bacillus megaterium
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 51740.80

構造登録者

Schubert, H.L.,Hill, C.P.,Warren, M.J. (登録日: 2008-06-12, 公開日: 2008-10-21, 最終更新日: 2024-03-20)

主引用文献

Schubert, H.L.,Rose, R.S.,Leech, H.K.,Brindley, A.A.,Hill, C.P.,Rigby, S.E.J.,Warren, M.J.
Structure and function of SirC from Bacillus megaterium: a metal-binding precorrin-2 dehydrogenase
Biochem.J., 415:257-263, 2008

PubMed Abstract: In Bacillus megaterium, the synthesis of vitamin B(12) (cobalamin) and sirohaem diverges at sirohydrochlorin along the branched modified tetrapyrrole biosynthetic pathway. This key intermediate is made by the action of SirC, a precorrin-2 dehydrogenase that requires NAD(+) as a cofactor. The structure of SirC has now been solved by X-ray crystallography to 2.8 A (1 A = 0.1 nm) resolution. The protein is shown to consist of three domains and has a similar topology to the multifunctional sirohaem synthases Met8p and the N-terminal region of CysG, both of which catalyse not only the dehydrogenation of precorrin-2 but also the ferrochelation of sirohydrochlorin to give sirohaem. Guided by the structure, in the present study a number of active-site residues within SirC were investigated by site-directed mutagenesis. No active-site general base was identified, although surprisingly some of the resulting protein variants were found to have significantly enhanced catalytic activity. Unexpectedly, SirC was found to bind metal ions such as cobalt and copper, and to bind them in an identical fashion with that observed in Met8p. It is suggested that SirC may have evolved from a Met8p-like protein by loss of its chelatase activity. It is proposed that the ability of SirC to act as a single monofunctional enzyme, in conjunction with an independent chelatase, may provide greater control over the intermediate at this branchpoint in the synthesis of sirohaem and cobalamin.

PubMed: 18588505
DOI: 10.1042/BJ20080785

実験手法

X-RAY DIFFRACTION (2.3 Å)