title: Dynamic elements govern the catalytic activity of CapE, a capsular polysaccharide-synthesizing enzyme from Staphylococcus aureus.
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.
authors.affiliation: Medical Proteomics Laboratory, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan; Department of Medical Genome Sciences, School of Frontier Sciences, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Miyafusa
authors.forename: Jose M M
authors.initials: JM
authors.lastname: Caaveiro
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Kouhei
authors.initials: K
authors.lastname: Tsumoto
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002238:Carbohydrate Epimerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006836:Hydro-Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D013211:Staphylococcus aureus / Q000201:enzymology*; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D006836:Hydro-Lyases; D002238:Carbohydrate Epimerases
keywords: CP; Capsular polysaccharide; Conformational change; HPLC; Pathogenic bacterium; SDR; SDR enzyme; SEC; Staphylococcus aureus; UDP-2-acetamido-2,6-deoxy-α-d-xylo-4-hexulose; UDP-2-acetamido-2,6-deoxy-α-l-arabino-4-hexulose; UDP-arabino-sugar; UDP-sugar; UDP-xylo-sugar; X-ray crystallography; capsular polysaccharide; high performance liquid chromatography; short-chain dehydrogenase/reductase; size-exclusion chromatography