title: D-alanine modification of a protease-susceptible outer membrane component by the Bordetella pertussis dra locus promotes resistance to antimicrobial peptides and polymorphonuclear leukocyte-mediated killing.
abstract: Bordetella pertussis is the causative agent of pertussis, a highly contagious disease of the human respiratory tract. Despite very high vaccine coverage, pertussis has reemerged as a serious threat in the United States and many developing countries. Thus, it is important to pursue research to discover unknown pathogenic mechanisms of B. pertussis. We have investigated a previously uncharacterized locus in B. pertussis, the dra locus, which is homologous to the dlt operons of Gram-positive bacteria. The absence of the dra locus resulted in increased sensitivity to the killing action of antimicrobial peptides (AMPs) and human phagocytes. Compared to the wild-type cells, the mutant cells bound higher levels of cationic proteins and peptides, suggesting that dra contributes to AMP resistance by decreasing the electronegativity of the cell surface. The presence of dra led to the incorporation of d-alanine into an outer membrane component that is susceptible to proteinase K cleavage. We conclude that dra encodes a virulence-associated determinant and contributes to the immune resistance of B. pertussis. With these findings, we have identified a new mechanism of surface modification in B. pertussis which may also be relevant in other Gram-negative pathogens.
authors.affiliation: Department of Microbiology and Immunology.
authors.forename: Neetu Kumra
authors.initials: NK
authors.lastname: Taneja
authors.forename: Tridib
authors.initials: T
authors.lastname: Ganguly
authors.forename: Lauren O
authors.initials: LO
authors.lastname: Bakaletz
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Nelson
authors.forename: Purnima
authors.initials: P
authors.lastname: Dubey
authors.forename: Leslie B
authors.initials: LB
authors.lastname: Poole
authors.forename: Rajendar
authors.initials: R
authors.lastname: Deora
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001886:Bordetella pertussis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D002478:Cells, Cultured; D024881:Drug Resistance, Bacterial; D019286:Endopeptidase K / Q000378:metabolism; D056426:Genetic Loci; D006801:Humans; D009504:Neutrophils / Q000276:immunology*; D059748:Proteolysis
chemical_list: D023181:Antimicrobial Cationic Peptides; D001425:Bacterial Outer Membrane Proteins; D019286:Endopeptidase K