Characterisation of Desulfovibrio vulgaris haem b synthase, a radical SAM family member

Lobo, Susana A.L., Lawrence, Andrew D., Romão, Célia V., Warren, Martin J. ORCID:, Teixeira, Miguel and Saraiva, Lígia M. (2014) Characterisation of Desulfovibrio vulgaris haem b synthase, a radical SAM family member. Biochimica et Biophysica Acta - Proteins and Proteomics, 1844 (7). pp. 1238-1247. ISSN 1570-9639

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An alternative route for haem b biosynthesis is operative in sulfate-reducing bacteria of the Desulfovibrio genus and in methanogenic Archaea. This pathway diverges from the canonical one at the level of uroporphyrinogen III and progresses via a distinct branch, where sirohaem acts as an intermediate precursor being converted into haem b by a set of novel enzymes, named the alternative haem biosynthetic proteins (Ahb). In this work, we report the biochemical characterisation of the Desulfovibrio vulgaris AhbD enzyme that catalyses the last step of the pathway. Mass spectrometry analysis showed that AhbD promotes the cleavage of S-adenosylmethionine (SAM) and converts iron-coproporphyrin III via two oxidative decarboxylations to yield haem b, methionine and the 5′-deoxyadenosyl radical. Electron paramagnetic resonance spectroscopy studies demonstrated that AhbD contains two [4Fe-4S]2 +/1 + centres and that binding of the substrates S-adenosylmethionine and iron-coproporphyrin III induces conformational modifications in both centres. Amino acid sequence comparisons indicated that D. vulgaris AhbD belongs to the radical SAM protein superfamily, with a GGE-like motif and two cysteine-rich sequences typical for ligation of SAM molecules and iron-sulfur clusters, respectively. A structural model of D. vulgaris AhbD with putative binding pockets for the iron-sulfur centres and the substrates SAM and iron-coproporphyrin III is discussed.

Item Type: Article
Additional Information: Funding Information: The work was funded by PEst-OE/EQB/LA0004/2011, FCT project PTDC/BBB-BQB/0937/2012 and the FCT student fellowship SFRH/BPD/63944/2009.
Uncontrolled Keywords: alternative haem biosynthesis,desulfovibrio,iron-coproporphyrin iii,iron-sulfur protein,s-adenosylmethionine,analytical chemistry,biophysics,biochemistry,molecular biology ,/dk/atira/pure/subjectarea/asjc/1600/1602
Faculty \ School: Faculty of Science
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Depositing User: LivePure Connector
Date Deposited: 20 Sep 2022 14:31
Last Modified: 24 Oct 2022 06:52
DOI: 10.1016/j.bbapap.2014.03.016

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