TY - JOUR
T1 - Phenotypic evidence that the function of the [Fe]-hydrogenase Hmd in Methanococcus maripaludis requires seven hcg (hmd co-occurring genes) but not hmdII
AU - Lie, Thomas J.
AU - Costa, Kyle C.
AU - Pak, Daniel
AU - Sakesan, Varun
AU - Leigh, John A.
PY - 2013/6
Y1 - 2013/6
N2 - 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.
AB - 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.
KW - Hydrogenotrophic methanogens
KW - Iron-guanylylpyridinol (FeGP) cofactor
KW - Iron-sulfur cluster-free hydrogenase
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U2 - 10.1111/1574-6968.12141
DO - 10.1111/1574-6968.12141
M3 - Letter
C2 - 23551135
AN - SCOPUS:84878420404
SN - 0378-1097
VL - 343
SP - 156
EP - 160
JO - FEMS Microbiology Letters
JF - FEMS Microbiology Letters
IS - 2
ER -