Molecular hijacking of siroheme for the synthesis of heme and d1 heme

Bali, Shilpa and Lawrence, Andrew D. and Lobo, Susana A.L. and Saraiva, Lígia M. and Golding, Bernard T. and Palmer, David J. and Howard, Mark J. and Ferguson, Stuart J. and Warren, Martin J. (2011) Molecular hijacking of siroheme for the synthesis of heme and d1 heme. Proceedings of the National Academy of Sciences of the United States of America, 108 (45). pp. 18260-18265. 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.1108228108

Abstract

Modified tetrapyrroles such as chlorophyll, heme, siroheme, vitamin B12, coenzyme F430, and heme d1 underpin a wide range of essential biological functions in all domains of life, and it is therefore surprising that the syntheses of many of these life pigments remain poorly understood. It is known that the construction of the central molecular framework of modified tetrapyrroles is mediated via a common, core pathway. Herein a further branch of the modified tetrapyrrole biosynthesis pathway is described in denitrifying and sulfate-reducing bacteria as well as the Archaea. This process entails the hijacking of siroheme, the prosthetic group of sulfite and nitrite reductase, and its processing into heme and d1 heme. The initial step in these transformations involves the decarboxylation of siroheme to give didecarboxysiroheme. For d1 heme synthesis this intermediate has to undergo the replacement of two propionate side chains with oxygen functionalities and the introduction of a double bond into a further peripheral side chain. For heme synthesis didecarboxysiroheme is converted into Fe-coproporphyrin by oxidative loss of two acetic acid side chains. Fe-coproporphyrin is then transformed into heme by the oxidative decarboxylation of two propionate side chains. The mechanisms of these reactions are discussed and the evolutionary significance of another role for siroheme is examined.

Item Type: Article
Uncontrolled keywords: enzymes; metabolic pathway; S-adenosylmethionine
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Sue Davies
Date Deposited: 09 Oct 2012 10:47
Last Modified: 14 Jul 2014 08:33
Resource URI: http://kar.kent.ac.uk/id/eprint/31426 (The current URI for this page, for reference purposes)
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