title: Serine protease autotransporters from Shigella flexneri and pathogenic Escherichia coli target a broad range of leukocyte glycoproteins.
abstract: The serine protease autotransporters of Enterobacteriaceae (SPATEs) are secreted by pathogenic Gram-negative bacteria through the autotransporter pathway. We previously classified SPATE proteins into two classes: cytotoxic (class 1) and noncytotoxic (class 2). Here, we show that Pic, a class 2 SPATE protein produced by Shigella flexneri 2a, uropathogenic and enteroaggregative Escherichia coli strains, targets a broad range of human leukocyte adhesion proteins. Substrate specificity was restricted to glycoproteins rich in O-linked glycans, including CD43, CD44, CD45, CD93, CD162 (PSGL-1; P-selectin glycoprotein ligand 1), and the surface-attached chemokine fractalkine, all implicated in leukocyte trafficking, migration, and inflammation. N-terminal sequencing of proteolytic products revealed Pic (protease involved in colonization) cleavage sites to occur before Thr or Ser residues. The purified carbohydrate sLewis-X implied in inflammation and malignancy inhibited cleavage of PSGL-1 by Pic. Exposure of human leukocytes to purified Pic resulted in polymorphonuclear cell activation, but impaired chemotaxis and transmigration; Pic-treated T cells underwent programmed cell death. We also show that the Pic-related protease Tsh/Hbp, implicated in extraintestinal infections, exhibited a spectrum of substrates similar to those cleaved by Pic. In the guinea pig keratoconjunctivitis model, a Shigella pic mutant induced greater inflammation than its parent strain. We suggest that the class-2 SPATEs represent unique immune-modulating bacterial virulence factors.
authors.affiliation: Center for Vaccine Development and Program of Comparative Medicine, Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA. fr3d@hscmail.mcc.virginia.edu
authors.forename: Fernando
authors.initials: F
authors.lastname: Ruiz-Perez
authors.forename: Rezwanul
authors.initials: R
authors.lastname: Wahid
authors.forename: Christina S
authors.initials: CS
authors.lastname: Faherty
authors.forename: Krishnan
authors.initials: K
authors.lastname: Kolappaswamy
authors.forename: Liliana
authors.initials: L
authors.lastname: Rodriguez
authors.forename: Araceli
authors.initials: A
authors.lastname: Santiago
authors.forename: Ebony
authors.initials: E
authors.lastname: Murphy
authors.forename: Alan
authors.initials: A
authors.lastname: Cross
authors.forename: Marcelo B
authors.initials: MB
authors.lastname: Sztein
authors.forename: James P
authors.initials: JP
authors.lastname: Nataro
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D002465:Cell Movement; D054428:Chemokine CX3CL1 / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology* / Q000502:physiology; D005434:Flow Cytometry; D006023:Glycoproteins / Q000378:metabolism*; D006168:Guinea Pigs; D054884:Host-Pathogen Interactions; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D007637:Keratoconjunctivitis / Q000382:microbiology; D017493:Leukocyte Common Antigens / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism* / Q000382:microbiology; D051917:Leukosialin / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D009154:Mutation; D018375:Neutrophil Activation; D010802:Phylogeny; D011951:Receptors, Complement / Q000378:metabolism; D057057:Serine Proteases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D012763:Shigella flexneri / Q000201:enzymology* / Q000502:physiology; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D054428:Chemokine CX3CL1; D006023:Glycoproteins; D018960:Hyaluronan Receptors; D051917:Leukosialin; D008562:Membrane Glycoproteins; C084882:P-selectin ligand protein; D011951:Receptors, Complement; C032402:complement 1q receptor; D017493:Leukocyte Common Antigens; C561930:Pic protein, Shigella flexneri; D057057:Serine Proteases