title: Autotransporter structure reveals intra-barrel cleavage followed by conformational changes.
abstract: Autotransporters are virulence factors produced by Gram-negative bacteria. They consist of two domains, an N-terminal 'passenger' domain and a C-terminal beta-domain. beta-domains form beta-barrel structures in the outer membrane while passenger domains are translocated into the extracellular space. In some autotransporters, the two domains are separated by proteolytic cleavage. Using X-ray crystallography, we solved the 2.7-A structure of the post-cleavage state of the beta-domain of EspP, an autotransporter produced by Escherichia coli strain O157:H7. The structure consists of a 12-stranded beta-barrel with the passenger domain-beta-domain cleavage junction located inside the barrel pore, approximately midway between the extracellular and periplasmic surfaces of the outer membrane. The structure reveals an unprecedented intra-barrel cleavage mechanism and suggests that two conformational changes occur in the beta-domain after cleavage, one conferring increased stability on the beta-domain and another restricting access to the barrel pore.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, US National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Travis J
authors.initials: TJ
authors.lastname: Barnard
authors.forename: Nathalie
authors.initials: N
authors.lastname: Dautin
authors.forename: Petra
authors.initials: P
authors.lastname: Lukacik
authors.forename: Harris D
authors.initials: HD
authors.lastname: Bernstein
authors.forename: Susan K
authors.initials: SK
authors.lastname: Buchanan
mesh_terms: D018360:Crystallography, X-Ray; D019453:Escherichia coli O157 / Q000737:chemistry; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006868:Hydrolysis; D017354:Point Mutation; D011487:Protein Conformation; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D055672:Static Electricity
chemical_list: D029968:Escherichia coli Proteins; C107189:EspP protein, E coli; D012697:Serine Endopeptidases