Phenotypic evidence that the function of the [Fe]-hydrogenase Hmd in Methanococcus maripaludis requires seven hcg (hmd co-occurring genes) but not hmdII

Thomas J. Lie, Kyle C. Costa, Daniel Pak, Varun Sakesan, John A. Leigh

Research output: Contribution to journalLetterpeer-review

12 Scopus citations

Abstract

The H2-dependent methylene-tetrahydromethanopterin dehydrogenase (Hmd), also known as the [Fe]-hydrogenase, is found only in methanogens without cytochromes. In contrast to the binuclear metal centers of the [NiFe]- and [FeFe]-hydrogenases, the [Fe]-hydrogenase contains only a single Fe atom, which is coordinated by a novel guanylylpyridinol cofactor in the active site. The biosynthesis of the cofactor is not well understood and the responsible genes are unknown. However, seven genes (hmd co-occurring genes, hcg) encoding proteins of unknown function are always associated with the hmd gene. In the model methanogen Methanococcus maripaludis, we used a genetic background in which a deletion of hmd had a distinct growth phenotype, and made null-mutations in each hcg gene as well as in a gene encoding the Hmd paralog HmdII, which is hypothesized to function as a scaffold for cofactor synthesis. Deletions in all seven hcg genes resulted in the same growth phenotype as a deletion in hmd, suggesting they are required for Hmd function. In all cases, genetic complementation of the mutation restored the wild-type phenotype. A deletion in hmdII had no effect.

Original languageEnglish (US)
Pages (from-to)156-160
Number of pages5
JournalFEMS Microbiology Letters
Volume343
Issue number2
DOIs
StatePublished - Jun 2013
Externally publishedYes

Keywords

  • Hydrogenotrophic methanogens
  • Iron-guanylylpyridinol (FeGP) cofactor
  • Iron-sulfur cluster-free hydrogenase

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