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Metalloenzymes; Protein structure; FeGP cofactor; Tetrahydrofolate; Tetrahydromethanopterin
Abstract:
[Fe]‐hydrogenase (Hmd) catalyzes the reversible hydrogenation of methenyl‐tetrahydromethanopterin (methenyl‐H4MPT+) with H2. H4MPT is a C1‐carrier of methanogenic archaea. One bacterial genus, Desulfurobacterium, contains putative genes for the Hmd paralog (HmdII) and the HcgA‐G proteins. The latter are involved in biosynthesis of the prosthetic group of Hmd, the iron‐guanylylpyridinol (FeGP) cofactor. This finding is intriguing because Hmd and HmdII strictly use H4MPT derivatives that are absent in most bacteria. We identified the presence of the FeGP cofactor in D. thermolithotrophum. The bacterial HmdII reconstituted with the FeGP cofactor catalyzed the enzyme reactions using the tetrahydrofolate derivatives, which are the bacterial C1 carrier, albeit with low enzymatic activities. Crystal structure provided the basis for how the enzyme was adapted to the bacterial C1‐carrier. This finding has impact on future biotechnology by developing the Hmd variants functioning in Bacteria
