title: The tail of KdsC: conformational changes control the activity of a haloacid dehalogenase superfamily phosphatase.
abstract: The phosphatase KdsC cleaves 3-deoxy-D-manno-octulosonate 8-phosphate to generate a molecule of inorganic phosphate and Kdo. Kdo is an essential component of the lipopolysaccharide envelope in Gram-negative bacteria. Because lipopolysaccharide is an important determinant of bacterial resistance and toxicity, KdsC is a potential target for novel antibacterial agents. KdsC belongs to the broad haloacid dehalogenase superfamily. In haloacid dehalogenase superfamily enzymes, substrate specificity and catalytic efficiency are generally dictated by a fold feature called the cap domain. It is therefore not clear why KdsC, which lacks a cap domain, is catalytically efficient and highly specific to 3-deoxy-D-manno-octulosonate 8-phosphate. Here, we present a set of seven structures of tetrameric Escherichia coli KdsC (ranging from 1.4 to 3.06 A in resolution) that model different intermediate states in its catalytic mechanism. A crystal structure of product-bound E. coli KdsC shows how the interface between adjacent monomers defines the active site pocket. Kdo is engaged in a network of polar and nonpolar interactions with residues at this interface, which explains substrate specificity. Furthermore, this structural and kinetic analysis strongly suggests that the binding of the flexible C-terminal region (tail) to the active site makes KdsC catalytically efficient by facilitating product release.
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Tapan
authors.initials: T
authors.lastname: Biswas
authors.forename: Li
authors.initials: L
authors.lastname: Yi
authors.forename: Parag
authors.initials: P
authors.lastname: Aggarwal
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.forename: John R
authors.initials: JR
authors.lastname: Rubin
authors.forename: Jeanne A
authors.initials: JA
authors.lastname: Stuckey
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Woodard
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Tsodikov
mesh_terms: D000900:Anti-Bacterial Agents; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D006867:Hydrolases / Q000737:chemistry* / Q000378:metabolism; D008070:Lipopolysaccharides; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D013379:Substrate Specificity; D013400:Sugar Acids / Q000378:metabolism; D013403:Sugar Phosphates / Q000378:metabolism
chemical_list: C415188:3-deoxyoctulosonate 8-phosphate; D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D008070:Lipopolysaccharides; D013400:Sugar Acids; D013403:Sugar Phosphates; D006867:Hydrolases; D010744:Phosphoric Monoester Hydrolases; C024329:3-deoxy-manno-octulosonate-8-phosphatase; C034507:2-haloacid dehalogenase