title: Bacillus anthracis protease InhA regulates BslA-mediated adhesion in human endothelial cells.
abstract: To achieve widespread dissemination in the host, Bacillus anthracis cells regulate their attachment to host endothelium during infection. Previous studies identified BslA (Bacillus anthracis S-layer Protein A), a virulence factor of B. anthracis, as necessary and sufficient for adhesion of vegetative cells to human endothelial cells. While some factors have been identified, bacteria-specific contributions to BslA mediated adhesion remain unclear. Using the attenuated vaccine Sterne 7702 strain of B. anthracis, we tested the hypothesis that InhA (immune inhibitor A), a B. anthracis protease, regulates BslA levels affecting the bacteria's ability to bind to endothelium. To test this, a combination of inhA mutant and complementation analysis in adhesion and invasion assays, Western blot and InhA inhibitor assays were employed. Results show InhA downregulates BslA activity reducing B. anthracis adhesion and invasion in human brain endothelial cells. BslA protein levels in ΔinhA bacteria were significantly higher than wild-type and complemented strains showing InhA levels and BslA expression are inversely related. BslA was sensitive to purified InhA degradation in a concentration- and time-dependent manner. Taken together these data support the role of InhA regulation of BslA-mediated vegetative cell adhesion and invasion.
authors.affiliation: Department of Biosciences and Biomedical Research Laboratory, George Mason University, 10650 Pyramid Place, Manassas, Virginia 20110, USA.
authors.forename: Jessica H
authors.initials: JH
authors.lastname: Tonry
authors.forename: Beth A
authors.initials: BA
authors.lastname: McNichol
authors.forename: Nalini
authors.initials: N
authors.lastname: Ramarao
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Chertow
authors.forename: Kwang Sik
authors.initials: KS
authors.lastname: Kim
authors.forename: Scott
authors.initials: S
authors.lastname: Stibitz
authors.forename: Olaf
authors.initials: O
authors.lastname: Schneewind
authors.forename: Fatah
authors.initials: F
authors.lastname: Kashanchi
authors.forename: Charles L
authors.initials: CL
authors.lastname: Bailey
authors.forename: Serguei
authors.initials: S
authors.lastname: Popov
authors.forename: Myung-Chul
authors.initials: MC
authors.lastname: Chung
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D000818:Animals; D001408:Bacillus anthracis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D001422:Bacterial Adhesion; D001639:Bicarbonates / Q000737:chemistry; D001921:Brain / Q000098:blood supply; D003470:Culture Media / Q000737:chemistry; D042783:Endothelial Cells / Q000382:microbiology*; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D054884:Host-Pathogen Interactions; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D045726:Metalloproteases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D050296:Microbial Viability; D055806:Microvessels / Q000166:cytology; D010618:Phenanthrolines / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D059748:Proteolysis; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D001639:Bicarbonates; D003470:Culture Media; D010618:Phenanthrolines; D011480:Protease Inhibitors; D037521:Virulence Factors; D045726:Metalloproteases; C025205:1,10-phenanthroline