title: New insights into the bacterial fitness-associated mechanisms revealed by the characterization of large plasmids of an avian pathogenic E. coli.
abstract: Extra-intestinal pathogenic E. coli (ExPEC), including avian pathogenic E. coli (APEC), pose a considerable threat to both human and animal health, with illness causing substantial economic loss. APEC strain χ7122 (O78∶K80∶H9), containing three large plasmids [pChi7122-1 (IncFIB/FIIA-FIC), pChi7122-2 (IncFII), and pChi7122-3 (IncI(2))]; and a small plasmid pChi7122-4 (ColE2-like), has been used for many years as a model strain to study the molecular mechanisms of ExPEC pathogenicity and zoonotic potential. We previously sequenced and characterized the plasmid pChi7122-1 and determined its importance in systemic APEC infection; however the roles of the other pChi7122 plasmids were still ambiguous. Herein we present the sequence of the remaining pChi7122 plasmids, confirming that pChi7122-2 and pChi7122-3 encode an ABC iron transport system (eitABCD) and a putative type IV fimbriae respectively, whereas pChi7122-4 is a cryptic plasmid. New features were also identified, including a gene cluster on pChi7122-2 that is not present in other E. coli strains but is found in Salmonella serovars and is predicted to encode the sugars catabolic pathways. In vitro evaluation of the APEC χ7122 derivative strains with the three large plasmids, either individually or in combinations, provided new insights into the role of plasmids in biofilm formation, bile and acid tolerance, and the interaction of E. coli strains with 3-D cultures of intestinal epithelial cells. In this study, we show that the nature and combinations of plasmids, as well as the background of the host strains, have an effect on these phenomena. Our data reveal new insights into the role of extra-chromosomal sequences in fitness and diversity of ExPEC in their phenotypes.
authors.affiliation: The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America. melha.mellata@asu.edu
authors.forename: Melha
authors.initials: M
authors.lastname: Mellata
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Maddux
authors.forename: Timothy
authors.initials: T
authors.lastname: Nam
authors.forename: Nicholas
authors.initials: N
authors.lastname: Thomson
authors.forename: Heidi
authors.initials: H
authors.lastname: Hauser
authors.forename: Mark P
authors.initials: MP
authors.lastname: Stevens
authors.forename: Suman
authors.initials: S
authors.lastname: Mukhopadhyay
authors.forename: Shameema
authors.initials: S
authors.lastname: Sarker
authors.forename: Aurélie
authors.initials: A
authors.lastname: Crabbé
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Nickerson
authors.forename: Javier
authors.initials: J
authors.lastname: Santander
authors.forename: Roy
authors.initials: R
authors.lastname: Curtiss
mesh_terms: D000818:Animals; D000940:Antigenic Variation / Q000235:genetics; D001483:Base Sequence; D001717:Birds / Q000235:genetics / Q000382:microbiology*; D002645:Chickens / Q000235:genetics / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000235:genetics / Q000662:veterinary; D056084:Genetic Fitness / Q000235:genetics*; D057131:Immune Evasion / Q000235:genetics; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010957:Plasmids / Q000032:analysis / Q000235:genetics*; D011201:Poultry Diseases / Q000235:genetics / Q000382:microbiology; D037521:Virulence Factors / Q000737:chemistry / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D037521:Virulence Factors