Kinetic and mechanistic characterization of the formyl-CoA transferase from Oxalobacter formigenes.
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Jonsson S, Ricagno S, Lindqvist Y, Richards NG
Kinetic and mechanistic characterization of the formyl-CoA transferase from Oxalobacter formigenes.
J Biol Chem. 2004 Aug 20;279(34):36003-12. Epub 2004 Jun 21.
- PubMed ID
- 15213226 [ View in PubMed]
- Abstract
Oxalobacter formigenes is an obligate anaerobe that colonizes the human gastrointestinal tract and employs oxalate breakdown to generate ATP in a novel process involving the interplay of two coupled enzymes and a membrane-bound oxalate:formate antiporter. Formyl-CoA transferase is a critical enzyme in oxalate-dependent ATP synthesis and is the first Class III CoA-transferase for which a high resolution, three-dimensional structure has been determined (Ricagno, S., Jonsson, S., Richards, N., and Lindqvist, Y. (2003) EMBO J. 22, 3210-3219). We now report the first detailed kinetic characterizations of recombinant, wild type formyl-CoA transferase and a number of site-specific mutants, which suggest that catalysis proceeds via a series of anhydride intermediates. Further evidence for this mechanistic proposal is provided by the x-ray crystallographic observation of an acylenzyme intermediate that is formed when formyl-CoA transferase is incubated with oxalyl-CoA. The catalytic mechanism of formyl-CoA transferase is therefore established and is almost certainly employed by all other members of the Class III CoA-transferase family.