title: Characterization of pic, a secreted protease of Shigella flexneri and enteroaggregative Escherichia coli.
abstract: We have identified and characterized a secreted protein, designated Pic, which is encoded on the chromosomes of enteroaggregative Escherichia coli (EAEC) 042 and Shigella flexneri 2457T. The product of the pic gene is synthesized as a 146.5-kDa precursor molecule which is processed at the N and C termini during secretion, allowing the release of a mature protein (109.8 kDa) into the culture supernatant. The deduced amino acid sequence of Pic shows high homology to autotransporter proteins, particularly a subgroup termed the SPATEs (serine protease autotransporters of the Enterobacteriaceae). Present in all members of this subgroup is a motif similar to the active sites of certain serine proteases. Pic catalyzes gelatin degradation, which can be abolished by disruption of the predicted proteolytic active site. Functional analysis of the Pic protein implicates this factor in mucinase activity, serum resistance, and hemagglutination. Our data suggest that Pic may be a multifunctional protein involved in enteric pathogenesis.
authors.affiliation: Center for Vaccine Development, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. ihenders@umaryland.edu
authors.forename: I R
authors.initials: IR
authors.lastname: Henderson
authors.forename: J
authors.initials: J
authors.lastname: Czeczulin
authors.forename: C
authors.initials: C
authors.lastname: Eslava
authors.forename: F
authors.initials: F
authors.lastname: Noriega
authors.forename: J P
authors.initials: JP
authors.lastname: Nataro
mesh_terms: D000328:Adult; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001770:Blood Bactericidal Activity; D003001:Cloning, Molecular; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000472:pathogenicity; D006384:Hemagglutination; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011817:Rabbits; D057057:Serine Proteases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012763:Shigella flexneri / Q000201:enzymology* / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D010450:Endopeptidases; C561930:Pic protein, Shigella flexneri; D057057:Serine Proteases