title: Characterization and functional analysis of AatB, a novel autotransporter adhesin and virulence factor of avian pathogenic Escherichia coli.
abstract: Autotransporter (AT) proteins constitute a large family of extracellular proteins that contribute to bacterial virulence. A novel AT adhesin gene, aatB, was identified in avian pathogenic Escherichia coli (APEC) DE205B via genomic analyses. The open reading frame of aatB was 1,017 bp, encoding a putative 36.3-kDa protein which contained structural motifs characteristic for AT proteins: a signal peptide, a passenger domain, and a translocator domain. The predicted three-dimensional structure of AatB consisted of two distinct domains, the C-terminal β-barrel translocator domain and an N-terminal passenger domain. The prevalence analyses of aatB in APEC indicated that aatB was detected in 26.4% (72/273) of APEC strains and was strongly associated with phylogenetic groups D and B2. Quantitative real-time reverse transcription-PCR analyses revealed that AatB expression was increased during infection in vitro and in vivo. Moreover, AatB could elicit antibodies in infected ducks, suggesting that AatB is involved in APEC pathogenicity. Thus, APEC DE205B strains with a mutated aatB gene and mutated strains complemented with the aatB gene were constructed. Inactivation of aatB resulted in a reduced capacity to adhere to DF-1 cells, defective virulence capacity in vivo, and decreased colonization capacity in lung during systemic infection compared with the capacities of the wild-type strain. Furthermore, these capacities were restored in the complementation strains. These results indicated that AatB makes a significant contribution to APEC virulence through bacterial adherence to host tissues in vivo and in vitro. In addition, biofilm formation assays with strain AAEC189 expressing AatB indicated that AatB mediates biofilm formation.
authors: Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China.
authors: Xiangkai
authors: X
authors: Zhuge
authors: Shaohui
authors: S
authors: Wang
authors: Hongjie
authors: H
authors: Fan
authors: Zihao
authors: Z
authors: Pan
authors: Jianluan
authors: J
authors: Ren
authors: Li
authors: L
authors: Yi
authors: Qingmei
authors: Q
authors: Meng
authors: Xuqiu
authors: X
authors: Yang
authors: Chengping
authors: C
authors: Lu
authors: Jianjun
authors: J
authors: Dai
mesh_terms: D018830:Adhesins, Escherichia coli / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001422:Bacterial Adhesion; D058491:Bacterial Load; D018441:Biofilms; D004372:Ducks / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008168:Lung / Q000382:microbiology; D016366:Open Reading Frames; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020539:Sequence Analysis, Protein; D017384:Sequence Deletion; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D018830:Adhesins, Escherichia coli; D037521:Virulence Factors
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