Characterization and distinction of two flagellar systems in extraintestinal pathogenic Escherichia coli PCN033.
Extraintestinal pathogenic Escherichia coli (ExPEC) can invade and colonize multiple extraintestinal tissues and can cause a wide range of infections; however the mechanisms of its pathogenicity are not well understood. Flagella contribute to the infection of E. coli strains by mediating adhesion and invasion. Our previous bioinformatic analysis revealed two flagella gene clusters in the genome of an ExPEC isolate, PCN033. One encodes the conventional flagellum system (Flag-1) and the other encodes the Flag-2 system, whose function is uncharacterized. Here we aimed to characterize these two flagellum systems and determine their contributions to the flagellum formation and certain pathogenicity-associated phenotypes. Our observations support the involvement of Flag-1 system, but not Flag-2 system, in the synthesis and maturation of the flagellum structure, and in mediating bacterial swimming and swarming. Moreover, flgD, which encodes a flagellar-hook scaffolding protein in the Flag-1 system, is required for flagellum assembly by influencing the production of FliC (flagellin). Deletion of flgD attenuated ExPEC strain PCN033 invasion and colonization in vivo, probably by affecting bacterial adhesion and invasion, and by reducing resistance to phagocytosis by circulating monocytes. In contrast, these phenotypes were not observed in the strain with deletion of lfgD, encoding the FlgD-like protein in the Flag-2 system. Taken together, these findings indicate that Flag-1 flagellum system is the determinative component of bacterial flagella that contributes to the infection.
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, China.
Feng
F
Liu
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, China.
Jiyang
J
Fu
Department of Veterinary Medicine, Foshan University, Foshan, Guangdong, China.
Canying
C
Liu
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, China.
Jing
J
Chen
Guangdong Lab for Animal Diseases/Guangdong Open Laboratory of Public Health, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
Minhua
M
Sun
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, China; Key Laboratory of development of veterinary diagnostic products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China.
Huanchun
H
Chen
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, China; Key Laboratory of development of veterinary diagnostic products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China. Electronic address: tanchen@mail.hzau.edu.cn.
Chen
C
Tan
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, China; Key Laboratory of development of veterinary diagnostic products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China. Electronic address: wangxr228@mail.hzau.edu.cn.
Xiangru
X
Wang
D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology; D054443:Cell Migration Assays; D004269:DNA, Bacterial / Q000235:genetics; D004927:Escherichia coli Infections / Q000378:metabolism / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D000072282:Extraintestinal Pathogenic Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity* / Q000502:physiology*; D005260:Female; D005407:Flagella / Q000235:genetics / Q000502:physiology*; D005408:Flagellin / Q000737:chemistry / Q000235:genetics; D051379:Mice; D005810:Multigene Family; D010587:Phagocytosis; D000067996:RAW 264.7 Cells; D017384:Sequence Deletion; D037521:Virulence Factors / Q000235:genetics
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C517779:FlgD protein, E coli; D037521:Virulence Factors; D005408:Flagellin
ExPEC; Flag-1; Flag-2; Flagella; flgD; lfgD