| Institution: | 1 Campbell Family Cancer Research Institute, Ontario Cancer Institute, University Health Network, Toronto Medical Discovery Tower, Toronto, Ontario, Canada M5G 1L72 Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada M5G 1L73 Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M5S 1A84 Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada M5S 1A85 Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8 |
| Abstract: | Autotransporters represent a large superfamily of known and putative virulence factors produced by Gram-negative bacteria. They consist of an N-terminal “passenger domain” responsible for the specific effector functions of the molecule and a C-terminal “β-domain” responsible for translocation of the passenger across the bacterial outer membrane. Here, we present the 2.5-Å crystal structure of the passenger domain of the extracellular serine protease EspP, produced by the pathogen Escherichia coli O157:H7 and a member of the serine protease autotransporters of Enterobacteriaceae (SPATEs). Like the previously structurally characterized SPATE passenger domains, the EspP passenger domain contains an extended right-handed parallel β-helix preceded by an N-terminal globular domain housing the catalytic function of the protease. Of note, however, is the absence of a second globular domain protruding from this β-helix. We describe the structure of the EspP passenger domain in the context of previous results and provide an alternative hypothesis for the function of the β-helix within SPATEs. |
