3lx4
Stepwise [FeFe]-hydrogenase H-cluster assembly revealed in the structure of HydA(deltaEFG)
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedComplex enzymes containing Fe-S clusters are ubiquitous in nature, where they are involved in a number of fundamental processes including carbon dioxide fixation, nitrogen fixation and hydrogen metabolism. Hydrogen metabolism is facilitated by the activity of three evolutionarily and structurally unrelated enzymes: the [NiFe]-hydrogenases, [FeFe]-hydrogenases and [Fe]-hydrogenases (Hmd). The catalytic core of the [FeFe]-hydrogenase (HydA), termed the H-cluster, exists as a [4Fe-4S] subcluster linked by a cysteine thiolate to a modified 2Fe subcluster with unique non-protein ligands. The 2Fe subcluster and non-protein ligands are synthesized by the hydrogenase maturation enzymes HydE, HydF and HydG; however, the mechanism, synthesis and means of insertion of H-cluster components remain unclear. Here we show the structure of HydA(DeltaEFG) (HydA expressed in a genetic background devoid of the active site H-cluster biosynthetic genes hydE, hydF and hydG) revealing the presence of a [4Fe-4S] cluster and an open pocket for the 2Fe subcluster. The structure indicates that H-cluster synthesis occurs in a stepwise manner, first with synthesis and insertion of the [4Fe-4S] subcluster by generalized host-cell machinery and then with synthesis and insertion of the 2Fe subcluster by specialized hydE-, hydF- and hydG-encoded maturation machinery. Insertion of the 2Fe subcluster presumably occurs through a cationically charged channel that collapses following incorporation, as a result of conformational changes in two conserved loop regions. The structure, together with phylogenetic analysis, indicates that HydA emerged within bacteria most likely from a Nar1-like ancestor lacking the 2Fe subcluster, and that this was followed by acquisition in several unicellular eukaryotes. Stepwise [FeFe]-hydrogenase H-cluster assembly revealed in the structure of HydA(DeltaEFG).,Mulder DW, Boyd ES, Sarma R, Lange RK, Endrizzi JA, Broderick JB, Peters JW Nature. 2010 May 13;465(7295):248-51. Epub 2010 Apr 25. PMID:20418861[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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