title: The type IV secretion system affects the expression of Omp25/Omp31 and the outer membrane properties of Brucella melitensis.
abstract: The type IV secretion system (T4SS) contributes to Brucella intracellular survival through its effector proteins. Comparative proteomic analysis showed that intracellular survival proteins are expressed differentially in a virB mutant. Interestingly, several outer membrane proteins (OMPs) are also differentially expressed, implying that T4SS might affect the OM properties of Brucella. To further evaluate the impact of T4SS on OM, in the present study, the OM proteomes were isolated and compared. Many more products of OMPs, particularly different products of the Omp25/Omp31 family, were found to be altered in the virB mutant. The transcription profiles of Omp25/Omp31 were different from those of their protein products, implying their regulation by virB at both transcriptional and post-transcriptional levels. The virB mutant aggregates at a high cell density and produces exopolysaccharide, a phenotype resembling that of the vjbR mutant. The virB mutant showed increased sensitivity to polymyxin B and decreased survival under oxidative, high-salt and high-osmolarity stresses, indicating drastic membrane alterations. These results indicated that in addition to being an effector protein secretion system, T4SS affects OM properties that might be important for the adaptation of Brucella to both in vitro and in vivo hostile environments.
authors.affiliation: Department of Infectious Disease Control, Institute of Disease Control and Prevention, Academy of Military Medical Science, Beijing, China.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Wang
authors.forename: Zeliang
authors.initials: Z
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Qiao
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Zhong
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.forename: Zhoujia
authors.initials: Z
authors.lastname: Wang
authors.forename: Xinying
authors.initials: X
authors.lastname: Du
authors.forename: Qing
authors.initials: Q
authors.lastname: Qu
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.forename: Leili
authors.initials: L
authors.lastname: Jia
authors.forename: Hongbin
authors.initials: H
authors.lastname: Song
authors.forename: Yansong
authors.initials: Y
authors.lastname: Sun
authors.forename: Liuyu
authors.initials: L
authors.lastname: Huang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D017347:Brucella melitensis / Q000187:drug effects / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D026901:Membrane Transport Proteins / Q000378:metabolism*; D050296:Microbial Viability / Q000187:drug effects; D009997:Osmotic Pressure; D018384:Oxidative Stress; D011112:Polymyxin B / Q000494:pharmacology; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D014176:Protein Biosynthesis; D020543:Proteome / Q000032:analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013312:Stress, Physiological; D014158:Transcription, Genetic
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D026901:Membrane Transport Proteins; D011135:Polysaccharides, Bacterial; D020543:Proteome; D011112:Polymyxin B