1,2-Propanediol Dehydration in Roseburia inulinivorans: STRUCTURAL BASIS FOR SUBSTRATE AND ENANTIOMER SELECTIVITY
Joseph W LaMattina1, Nicholas D Keul1, Pierre Reitzer1
1From the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602 and.
Abstract:
Glycyl radical enzymes (GREs) represent a diverse superfamily of enzymes that utilize a radical mechanism to catalyze difficult, but often essential, chemical reactions. In this work we present the first biochemical and structural data for a GRE-type diol dehydratase from the organism Roseburia inulinivorans (RiDD). Despite high sequence (48% identity) and structural similarity to the GRE-type glycerol dehydratase from Clostridium butyricum, we demonstrate that the RiDD is in fact a diol dehydratase. In addition, the RiDD will utilize both (S)-1,2-propanediol and (R)-1,2-propanediol as a substrate, with an observed preference for the S enantiomer. Based on the new structural information we developed and successfully tested a hypothesis that explains the functional differences we observe.
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