title: Calcium-induced folding and stabilization of the Pseudomonas aeruginosa alkaline protease.
abstract: Pseudomonas aeruginosa is an opportunistic pathogen that contributes to the mortality of immunocompromised individuals and patients with cystic fibrosis. Pseudomonas infection presents clinical challenges due to its ability to form biofilms and modulate host-pathogen interactions through the secretion of virulence factors. The calcium-regulated alkaline protease (AP), a member of the repeats in toxin (RTX) family of proteins, is implicated in multiple modes of infection. A series of full-length and truncation mutants were purified for structural and functional studies to evaluate the role of Ca(2+) in AP folding and activation. We find that Ca(2+) binding induces RTX folding, which serves to chaperone the folding of the protease domain. Subsequent association of the RTX domain with an N-terminal α-helix stabilizes AP. These results provide a basis for the Ca(2+)-mediated regulation of AP and suggest mechanisms by which Ca(2+) regulates the RTX family of virulence factors.
authors.affiliation: Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.forename: James F
authors.initials: JF
authors.lastname: Conway
authors.forename: Patrick H
authors.initials: PH
authors.lastname: Thibodeau
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D004795:Enzyme Stability / Q000502:physiology; D018832:Molecular Chaperones / Q000378:metabolism*; D017510:Protein Folding; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000472:pathogenicity; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D018832:Molecular Chaperones; D037521:Virulence Factors; D010450:Endopeptidases; C087822:alkaline protease; D002118:Calcium