title: Transcriptional responses of uropathogenic Escherichia coli to increased environmental osmolality caused by salt or urea.
abstract: Uropathogenic Escherichia coli (UPEC) is the most common causative agent of urinary tract infections in humans. The majority of urinary infections develop via ascending route through the urethra, where bacterial cells come in contact with human urine prior to reaching the bladder or kidneys. Since urine contains significant amounts of inorganic ions and urea, it imposes osmotic and denaturing stresses on bacterial cells. In this study, we determined the transcriptional adaptive responses of UPEC strain CFT073 to the presence of 0.3 M NaCl or 0.6 M urea in the growth medium. The cell responses to these two osmolytes were drastically different. Although most of the genes of the osmotically inducible regulon were overexpressed in medium with salt, urea failed to stimulate osmotic stress response. At the same time, UPEC colonization genes encoding type 1 and F1C fimbriae and capsule biosynthesis were transcriptionally induced in the presence of urea but did not respond to increased salt concentration. We speculate that urea can potentially be sensed by uropathogenic bacteria to initiate infection program. In addition, several molecular chaperone genes were overexpressed in the presence of urea, whereas adding NaCl to the medium led to an upregulation of a number of anaerobic metabolism pathways.
authors.affiliation: Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Withman
authors.forename: Thusitha S
authors.initials: TS
authors.lastname: Gunasekera
authors.forename: Pavani
authors.initials: P
authors.lastname: Beesetty
authors.forename: Richard
authors.initials: R
authors.lastname: Agans
authors.forename: Oleg
authors.initials: O
authors.lastname: Paliy
mesh_terms: D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects* / Q000235:genetics; D014508:Urea / Q000494:pharmacology*; D056689:Uropathogenic Escherichia coli / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; C097578:IbpA protein, E coli; D012333:RNA, Messenger; D036781:Fimbriae Proteins; D012965:Sodium Chloride; D014508:Urea