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Publication Abstract from PubMed

S-Adenosyl-L-homocysteine hydrolase (SAHase) is involved in the enzymatic regulation of S-adenosyl-L-methionine (SAM)-dependent methylation reactions. After methyl-group transfer from SAM, S-adenosyl-L-homocysteine (SAH) is formed as a byproduct, which in turn is hydrolyzed to adenosine (Ado) and homocysteine (Hcy) by SAHase. The crystal structure of BeSAHase, an SAHase from Bradyrhizobium elkanii, which is a nitrogen-fixing bacterial symbiont of legume plants, was determined at 1.7 A resolution, showing the domain organization (substrate-binding domain, NAD(+) cofactor-binding domain and dimerization domain) of the subunits. The protein crystallized in its biologically relevant tetrameric form, with three subunits in a closed conformation enforced by complex formation with the Ado product of the enzymatic reaction. The fourth subunit is ligand-free and has an open conformation. The BeSAHase structure therefore provides a unique snapshot of the domain movement of the enzyme induced by the binding of its natural ligands.

An enzyme captured in two conformational states: crystal structure of S-adenosyl-L-homocysteine hydrolase from Bradyrhizobium elkanii.,Manszewski T, Singh K, Imiolczyk B, Jaskolski M Acta Crystallogr D Biol Crystallogr. 2015 Dec 1;71(Pt 12):2422-32. doi:, 10.1107/S1399004715018659. Epub 2015 Nov 26. PMID:26627650^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.