title: Purification and characterization of KpsT, the ATP-binding component of the ABC-capsule exporter of Escherichia coli K1.
abstract: The K1 capsule, an alpha(2,8)-linked polymer of sialic acid, is an important virulence determinant of invasive Escherichia coli. The 17-kb kps gene cluster of E. coli K1 encodes the information necessary for capsule expression at the cell surface. Two proteins, KpsM and KpsT, play a role in the transport of capsular polysaccharide across the cytoplasmic membrane, utilizing the energy from ATP hydrolysis. They belong to the ATP-binding cassette superfamily of transport proteins. In this study, we purified KpsT in its native form and show that the purified protein is able to bind ATP, undergo an ATP-dependent conformational change and hydrolyze ATP. Protease accessibility studies demonstrate the in vivo interaction between KpsM and KpsT.
authors.affiliation: Department of Microbiology and Immunology, University of Rochester Medical Center, 601 Elmwood Ave., Box 672, Rochester, NY 14642, USA.
authors.forename: Christiane J
authors.initials: CJ
authors.lastname: Nsahlai
authors.forename: Richard P
authors.initials: RP
authors.lastname: Silver
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics; D001386:Azides / Q000493:pharmacokinetics; D016667:Bacterial Capsules / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010777:Photochemistry; D010957:Plasmids; D017434:Protein Structure, Tertiary
chemical_list: D018528:ATP-Binding Cassette Transporters; D001386:Azides; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D010761:Phosphorus Radioisotopes; C068104:kpsM protein, E coli; C068103:kpsT protein, E coli; C017040:8-azidoadenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases