title: TolC promotes ExPEC biofilm formation and curli production in response to medium osmolarity.
abstract: While a high osmolarity medium activates Cpx signaling and causes CpxR to repress csgD expression, and efflux protein TolC protein plays an important role in biofilm formation in Escherichia coli, whether TolC also responds to an osmolarity change to regulate biofilm formation in extraintestinal pathogenic E. coli (ExPEC) remains unknown. In this study, we constructed ΔtolC mutant and complement ExPEC strains to investigate the role of TolC in the retention of biofilm formation and curli production capability under different osmotic conditions. The ΔtolC mutant showed significantly decreased biofilm formation and lost the ability to produce curli fimbriae compared to its parent ExPEC strain PPECC42 when cultured in M9 medium or 1/2 M9 medium of increased osmolarity with NaCl or sucrose at 28°C. However, biofilm formation and curli production levels were restored to wild-type levels in the ΔtolC mutant in 1/2 M9 medium. We propose for the first time that TolC protein is able to form biofilm even under high osmotic stress. Our findings reveal an interplay between the role of TolC in ExPEC biofilm formation and the osmolarity of the surrounding environment, thus providing guidance for the development of a treatment for ExPEC biofilm formation.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Xian-Rong
authors.initials: XR
authors.lastname: Meng
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Li-Yuan
authors.initials: LY
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Tan
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Zi-Li
authors.initials: ZL
authors.lastname: Li
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Mei
authors.identifier: 0000-0003-4718-2326
authors.initials: M
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Huan-Chun
authors.initials: HC
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Ding-Ren
authors.initials: DR
authors.lastname: Bi
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan, Hubei 430070, China.
authors.forename: Shao-Wen
authors.initials: SW
authors.lastname: Li
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D049109:Cell Proliferation; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009994:Osmolar Concentration; D009997:Osmotic Pressure / Q000502:physiology*; D012965:Sodium Chloride
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C073126:tolC protein, E coli; C077481:Crl protein, Bacteria; D012965:Sodium Chloride