Siroheme synthase

Function

Siroheme synthase (CysG) catalyzes the reduction of sulfite to sulfide or nitrite to ammonia^[1]. CysG substrate is a tetrapyrrole.

Structural highlights

The tetrapyrrole in siroheme is heavily negatively charged because of the 8 acetyl and propionyl carboxylates at the corners of the siroheme and it interacts with . Five of these residues are positively charged .

Salmonella typhimurium siroheme synthase complex with Co-sirohydrochlorin, SAH and Cl- ion (PDB code 6p5z)

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Siroheme synthase 3D structuresSiroheme synthase 3D structures

Updated on 03-July-2022

1pjq – StCysG + SAH – Salmonella typhimurium
1pjt, 6p7c, 6p7d, 6pqz, 6pr0, 6pr1, 6pr2, 6pr3, 6pr4, 6ulu – StCysG (mutant) + SAH
6p5z – StCysG + SAH + Co-sirohydrochlorin
1pjs – StCysG + SAH + NAD
6p5x – StCysG (mutant) + SAH + substrate
6veb – StCysG (mutant) + SAH + NAD + pecorrin

ReferencesReferences

↑ Pennington JM, Kemp M, McGarry L, Chen Y, Stroupe ME. Siroheme synthase orients substrates for dehydrogenase and chelatase activities in a common active site. Nat Commun. 2020 Feb 13;11(1):864. doi: 10.1038/s41467-020-14722-1. PMID:32054833 doi:http://dx.doi.org/10.1038/s41467-020-14722-1

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Michal Harel, Alexander Berchansky

[1] Pennington JM, Kemp M, McGarry L, Chen Y, Stroupe ME. Siroheme synthase orients substrates for dehydrogenase and chelatase activities in a common active site. Nat Commun. 2020 Feb 13;11(1):864. doi: 10.1038/s41467-020-14722-1. PMID:32054833 doi:http://dx.doi.org/10.1038/s41467-020-14722-1

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