title: The omptins of Yersinia pestis and Salmonella enterica cleave the reactive center loop of plasminogen activator inhibitor 1.
abstract: Plasminogen activator inhibitor 1 (PAI-1) is a serine protease inhibitor (serpin) and a key molecule that regulates fibrinolysis by inactivating human plasminogen activators. Here we show that two important human pathogens, the plague bacterium Yersinia pestis and the enteropathogen Salmonella enterica serovar Typhimurium, inactivate PAI-1 by cleaving the R346-M347 bait peptide bond in the reactive center loop. No cleavage of PAI-1 was detected with Yersinia pseudotuberculosis, an oral/fecal pathogen from which Y. pestis has evolved, or with Escherichia coli. The cleavage and inactivation of PAI-1 were mediated by the outer membrane proteases plasminogen activator Pla of Y. pestis and PgtE protease of S. enterica, which belong to the omptin family of transmembrane endopeptidases identified in Gram-negative bacteria. Cleavage of PAI-1 was also detected with the omptins Epo of Erwinia pyrifoliae and Kop of Klebsiella pneumoniae, which both belong to the same omptin subfamily as Pla and PgtE, whereas no cleavage of PAI-1 was detected with omptins of Shigella flexneri or E. coli or the Yersinia chromosomal omptins, which belong to other omptin subfamilies. The results reveal a novel serpinolytic mechanism by which enterobacterial species expressing omptins of the Pla subfamily bypass normal control of host proteolysis.
authors.affiliation: Department of Biosciences, PO Box 56, University of Helsinki, FI 00014 Helsinki, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Haiko
authors.forename: Liisa
authors.initials: L
authors.lastname: Laakkonen
authors.forename: Katri
authors.initials: K
authors.lastname: Juuti
authors.forename: Nisse
authors.initials: N
authors.lastname: Kalkkinen
authors.forename: Timo K
authors.initials: TK
authors.lastname: Korhonen
mesh_terms: D019295:Computational Biology; D010802:Phylogeny; D017395:Plasminogen Activator Inhibitor 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019779:Salmonella enterica / Q000201:enzymology*; D012697:Serine Endopeptidases / Q000145:classification / Q000378:metabolism*; D015010:Yersinia pestis / Q000201:enzymology*
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D012697:Serine Endopeptidases; C057840:omptin outer membrane protease