Issue 18, 2019

Structure of sirohydrochlorin ferrochelatase SirB: the last of the structures of the class II chelatase family

Abstract

The crystal structure of Bacillus subtilis SirB, which catalyses the insertion of Fe2+ into the substrate sirohydrochlorin (SHC) in siroheme biosynthesis, is reported herein as the last of the structures of class II chelatases. The structure of SirB with Co2+ showed that the active site of SirB is located at the N-terminal domain with metal-binding amino acid residues His10, Glu43, and His76, which was also predicted for CbiX, but is distinct from the C-terminal active sites of CbiK and HemH. The biosynthetic model reactions using SirB, Co2+ and uroporphyrin I or protoporphyrin IX as a SHC analogue revealed that SirB showed chelatase activity for uroporphyrin I, but not for protoporphyrin IX. Simulations of tetrapyrroles docking to SirB provided an insight into its tetrapyrrole substrate recognition: SHC and uroporphyrin I were suitably bound beside the Co2+ ion-binding site at the active site cavity; protoporphyrin IX was also docked to the active site but its orientation was different from those of the other two tetrapyrroles. Summarizing the present data, it was proposed that the key structural features for substrate recognition of SirB could be the hydrophobic area at the active site as well as the substituents of the tetrapyrroles.

Graphical abstract: Structure of sirohydrochlorin ferrochelatase SirB: the last of the structures of the class II chelatase family

Supplementary files

Article information

Article type
Paper
Submitted
29 nov 2018
Accepted
12 fev 2019
First published
19 fev 2019

Dalton Trans., 2019,48, 6083-6090

Structure of sirohydrochlorin ferrochelatase SirB: the last of the structures of the class II chelatase family

T. Fujishiro, Y. Shimada, R. Nakamura and M. Ooi, Dalton Trans., 2019, 48, 6083 DOI: 10.1039/C8DT04727H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements