title: Characterization of BcaA, a putative classical autotransporter protein in Burkholderia pseudomallei.
abstract: Burkholderia pseudomallei is a tier 1 select agent, and the causative agent of melioidosis, a disease with effects ranging from chronic abscesses to fulminant pneumonia and septic shock, which can be rapidly fatal. Autotransporters (ATs) are outer membrane proteins belonging to the type V secretion system family, and many have been shown to play crucial roles in pathogenesis. The open reading frame Bp1026b_II1054 (bcaA) in B. pseudomallei strain 1026b is predicted to encode a classical autotransporter protein with an approximately 80-kDa passenger domain that contains a subtilisin-related domain. Immediately 3' to bcaA is Bp11026_II1055 (bcaB), which encodes a putative prolyl 4-hydroxylase. To investigate the role of these genes in pathogenesis, large in-frame deletion mutations of bcaA and bcaB were constructed in strain Bp340, an efflux pump mutant derivative of the melioidosis clinical isolate 1026b. Comparison of Bp340ΔbcaA and Bp340ΔbcaB mutants to wild-type B. pseudomallei in vitro demonstrated similar levels of adherence to A549 lung epithelial cells, but the mutant strains were defective in their ability to invade these cells and to form plaques. In a BALB/c mouse model of intranasal infection, similar bacterial burdens were observed after 48 h in the lungs and liver of mice infected with Bp340ΔbcaA, Bp340ΔbcaB, and wild-type bacteria. However, significantly fewer bacteria were recovered from the spleen of Bp340ΔbcaA-infected mice, supporting the idea of a role for this AT in dissemination or in survival in the passage from the site of infection to the spleen.
authors: Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA.
authors: Cristine G
authors: CG
authors: Campos
authors: Luke
authors: L
authors: Borst
authors: Peggy A
authors: PA
authors: Cotter
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D058491:Bacterial Load; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D016957:Burkholderia pseudomallei / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D002460:Cell Line; D004252:DNA Mutational Analysis; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000382:microbiology; D005260:Female; D006801:Humans; D008099:Liver / Q000382:microbiology; D008168:Lung / Q000382:microbiology; D008554:Melioidosis / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D021381:Protein Transport; D017384:Sequence Deletion; D013154:Spleen / Q000382:microbiology; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D058947:Bacterial Secretion Systems; D037521:Virulence Factors