Evolution in a family of chelatases facilitated by the introduction of active site asymmetry and protein oligomerization

Romao, Célia V. and Ladakis, Dimitrios and Lobo, Susana A.L. and Carrondo, Maria A. and Brindley, Amanda A. and Deery, Evelyne and Matias, Pedro M. and Pickersgill, Richard W. and Saraiva, Lígia M. and Warren, Martin J. (2011) Evolution in a family of chelatases facilitated by the introduction of active site asymmetry and protein oligomerization. Proceedings of the National Academy of Sciences of the United States of America, 108 (1). pp. 97-102. ISSN 0027-8424. (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/10.1073/pnas.1014298108

Abstract

The class II chelatases associated with heme, siroheme, and cobalamin biosynthesis are structurally related enzymes that insert a specific metal ion (Fe2+ or Co2+) into the center of a modified tetrapyrrole (protoporphyrin or sirohydrochlorin). The structures of two related class II enzymes, CbiXS from Archaeoglobus fulgidus and CbiK from Salmonella enterica, that are responsible for the insertion of cobalt along the cobalamin biosynthesis pathway are presented in complex with their metallated product. A further structure of a CbiK from Desulfovibrio vulgaris Hildenborough reveals how cobalt is bound at the active site. The crystal structures show that the binding of sirohydrochlorin is distinctly different to porphyrin binding in the protoporphyrin ferrochelatases and provide a molecular overview of the mechanism of chelation. The structures also give insights into the evolution of chelatase form and function. Finally, the structure of a periplasmic form of Desulfovibrio vulgaris Hildenborough CbiK reveals a novel tetrameric arrangement of its subunits that are stabilized by the presence of a heme b cofactor. Whereas retaining colbaltochelatase activity, this protein has acquired a central cavity with the potential to chaperone or transport metals across the periplasmic space, thereby evolving a new use for an ancient protein subunit.

Item Type: Article
Uncontrolled keywords: enzyme mechanism; tetrapyrrole biosynthesis
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Sue Davies
Date Deposited: 09 Oct 2012 10:42
Last Modified: 17 Jul 2014 11:50
Resource URI: http://kar.kent.ac.uk/id/eprint/31421 (The current URI for this page, for reference purposes)
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