The euryarchaeon Methanosarcina acetivorans has no homologues of the first three enzymes that produce the essential methanogenic coenzyme M (2-mercaptoethanesulfonate) in Methanocaldococcus jannaschii. A single M. acetivorans gene was heterologously expressed to produce a functional sulfopyruvate decarboxylase protein, the fourth canonical enzyme in this biosynthetic pathway. An adjacent gene, at locus MA3297, encodes one of the organism's two threonine synthase homologues. When both paralogues from this organism were expressed in an Escherichia coli threonine synthase mutant, the MA1610 gene complemented the thrC mutation, whereas the MA3297 gene did not. Both PLP (pyridoxal 5′-phosphate)-dependent proteins were heterologously expressed and purified, but only the MA1610 protein catalysed the canonical threonine synthase reaction. The MA3297 protein specifically catalysed a new β-replacement reaction that converted L-phosphoserine and sulfite into L-cysteate and inorganic phosphate. This oxygen-independent mode of sulfonate biosynthesis exploits the facile nucleophilic addition of sulfite to an α,β-unsaturated intermediate (PLP-bound dehydroalanine). An amino acid sequence comparison indicates that cysteate synthase evolved from an ancestral threonine synthase through gene duplication, and the remodelling of active site loop regions by amino acid insertion and substitutions. The cysteate product can be converted into sulfopyruvate by an aspartate aminotransferase enzyme, establishing a new convergent pathway for coenzyme M biosynthesis that appears to function in members of the orders Methanosarcinales and Methanomicrobiales. These differences in coenzyme M biosynthesis afford the opportunity to develop methanogen inhibitors that discriminate between the classes of methanogenic archaea.
Skip Nav Destination
Article navigation
December 2009
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
- PDF Icon PDF LinkEditorial Board
Research Article|
December 10 2009
Convergent evolution of coenzyme M biosynthesis in the Methanosarcinales: cysteate synthase evolved from an ancestral threonine synthase
David E. Graham;
David E. Graham
1
*Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, U.S.A.
†Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, U.S.A.
1To whom correspondence should be addressed (email degraham@mail.utexas.edu).
Search for other works by this author on:
Stephanie M. Taylor;
Stephanie M. Taylor
*Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, U.S.A.
Search for other works by this author on:
Rachel Z. Wolf;
Rachel Z. Wolf
†Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, U.S.A.
Search for other works by this author on:
Seema C. Namboori
Seema C. Namboori
†Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, U.S.A.
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
July 02 2009
Revision Received:
September 10 2009
Accepted:
September 17 2009
Accepted Manuscript online:
September 17 2009
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2009 Biochemical Society
2009
Biochem J (2009) 424 (3): 467–478.
Article history
Received:
July 02 2009
Revision Received:
September 10 2009
Accepted:
September 17 2009
Accepted Manuscript online:
September 17 2009
Citation
David E. Graham, Stephanie M. Taylor, Rachel Z. Wolf, Seema C. Namboori; Convergent evolution of coenzyme M biosynthesis in the Methanosarcinales: cysteate synthase evolved from an ancestral threonine synthase. Biochem J 15 December 2009; 424 (3): 467–478. doi: https://doi.org/10.1042/BJ20090999
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.