title: The transfer-messenger RNA-small protein B system plays a role in avian pathogenic Escherichia coli pathogenicity.
abstract: Extraintestinal pathogenic Escherichia coli (ExPEC) is capable of colonizing outside of the intestinal tract and evolving into a systemic infection. Avian pathogenic E. coli (APEC) is a member of the ExPEC group and causes avian colibacillosis. Transfer-mRNA-small protein B (tmRNA-SmpB)-mediated trans-translation is a bacterial translational control system that directs the modification and degradation of proteins, the biosynthesis of which has stalled or has been interrupted, facilitating the rescue of ribosomes stalled at the 3' ends of defective mRNAs that lack a stop codon. We found that disruption of one, or both, of the smpB or ssrA genes significantly decreased the virulence of the APEC strain E058, as assessed by chicken infection assays. Furthermore, the mutants were obviously attenuated in colonization and persistence assays. The results of quantitative real-time reverse transcription-PCR analysis indicated that the transcription levels of the transcriptional regulation gene rfaH and the virulence genes kpsM, chuA, and iss were significantly decreased compared to those of the wild-type strain. Macrophage infection assays showed that the mutant strains reduced the replication and/or survival ability in the macrophage HD11 cell line compared to that of the parent strain, E058. However, no significant differences were observed in ingestion by macrophages and in chicken serum resistance between the mutant and the wild-type strains. These data indicate that the tmRNA-SmpB system is important in the pathogenesis of APEC O2 strain E058.
authors.affiliation: Animal Infectious Disease Laboratory, Ministry of Agriculture, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Mu
authors.forename: Haixia
authors.initials: H
authors.lastname: Huan
authors.forename: Huiqing
authors.initials: H
authors.lastname: Xu
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Gao
authors.forename: Liping
authors.initials: L
authors.lastname: Xiong
authors.forename: Ruxia
authors.initials: R
authors.lastname: Gao
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.forename: Xiufan
authors.initials: X
authors.lastname: Liu
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D008264:Macrophages / Q000276:immunology / Q000382:microbiology; D050296:Microbial Viability; D011201:Poultry Diseases / Q000382:microbiology / Q000473:pathology; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D016601:RNA-Binding Proteins; D037521:Virulence Factors; C430328:small protein B