Dynamic elements govern the catalytic activity of CapE,a capsular polysaccharide-synthesizing enzyme from Staphylococcus aureus |
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Authors: | Takamitsu Miyafusa Jose M.M. Caaveiro Yoshikazu Tanaka Kouhei Tsumoto |
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Affiliation: | 1. Medical Proteomics Laboratory, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan;2. Department of Medical Genome Sciences, School of Frontier Sciences, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan;3. Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan |
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Abstract: | CapE is an essential enzyme for the synthesis of capsular polysaccharide (CP) of pathogenic strains of Staphylococcus aureus. Herein we demonstrate that CapE is a 5-inverting 4,6-dehydratase enzyme. However, in the absence of downstream enzymes, CapE catalyzes an additional reaction (5-back-epimerization) affording a by-product under thermodynamic control. Single-crystal X-ray crystallography was employed to identify the structure of the by-product. The structural analysis reveals a network of coordinated motions away from the active site governing the enzymatic activity of CapE. A second dynamic element (the latch) regulates the enzymatic chemoselectivity. The validity of these mechanisms was evaluated by site-directed mutagenesis. |
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Keywords: | Pathogenic bacterium Capsular polysaccharide X-ray crystallography Conformational change SDR enzyme UDP-sugar Staphylococcus aureus |
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