title: Vibrio cholerae toxin-coregulated pilus structure analyzed by hydrogen/deuterium exchange mass spectrometry.
abstract: The bacterial pathogen Vibrio cholerae uses toxin-coregulated pili (TCP) to colonize the human intestine, causing the severe diarrheal disease cholera. TCP are long, thin, flexible homopolymers of the TcpA subunit that self-associate to hold cells together in microcolonies and serve as the receptor for the cholera toxin phage. To better understand TCP's roles in pathogenesis, we characterized its structure using hydrogen/deuterium exchange mass spectrometry and computational modeling. We show that the pilin subunits are held together by tight packing of the N-terminal alpha helices, but loose packing of the C-terminal globular domains leaves substantial gaps on the filament surface. These gaps expose a glycine-rich, amphipathic segment of the N-terminal alpha-helix, contradicting the consensus view that this region is buried in the filament core. Our results explain extreme filament flexibility, suggest a molecular basis for pilus-pilus interactions, and reveal a previously unrecognized therapeutic target for V. cholerae and other enteric pathogens.
authors.affiliation: Molecular Biology and Biochemistry Department, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada.
authors.forename: Juliana
authors.initials: J
authors.lastname: Li
authors.forename: Mindy S
authors.initials: MS
authors.lastname: Lim
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
authors.forename: Melissa
authors.initials: M
authors.lastname: Brock
authors.forename: Michael E
authors.initials: ME
authors.lastname: Pique
authors.forename: Virgil L
authors.initials: VL
authors.lastname: Woods
authors.forename: Lisa
authors.initials: L
authors.lastname: Craig
mesh_terms: D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000737:chemistry / Q000633:toxicity*; D002771:Cholera / Q000382:microbiology; D017124:Conserved Sequence; D003967:Diarrhea / Q000382:microbiology; D010861:Fimbriae, Bacterial / Q000737:chemistry / Q000648:ultrastructure*; D006801:Humans; D007422:Intestines / Q000382:microbiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D014734:Vibrio cholerae / Q000472:pathogenicity / Q000648:ultrastructure*
chemical_list: D001427:Bacterial Toxins