title: Transcriptional Control of Dual Transporters Involved in α-Ketoglutarate Utilization Reveals Their Distinct Roles in UropathogenicEscherichia coli.
abstract: UropathogenicEscherichia coli(UPEC) are the primary causative agents of urinary tract infections. Some UPEC isolates are able to infect renal proximal tubule cells, and can potentially cause pyelonephritis. We have previously shown that to fulfill their physiological roles renal proximal tubule cells accumulate high concentrations of α-ketoglutarate (KG) and that gene clusterc5032-c5039contribute to anaerobic utilization of KG by UPEC str. CFT073, thereby promoting itsin vivofitness. Given the importance of utilizing KG for UPEC, this study is designed to investigate the roles of two transporters KgtP and C5038 in KG utilization, their transcriptional regulation, and their contributions to UPEC fitnessin vivo. Our phylogenetic analyses support thatkgtPis a widely conserved locus in commensal and pathogenicE. coli, while UPEC-associatedc5038was acquired through horizontal gene transfer. Global anaerobic transcriptional regulators Fumarate and nitrate reduction (FNR) and ArcA inducedc5038expression in anaerobiosis, and C5038 played a major role in anaerobic growth on KG. KgtP was required for aerobic growth on KG, and its expression was repressed by FNR and ArcA under anaerobic conditions. Analyses of FNR and ArcA binding sites and results of EMS assays suggest that FNR and ArcA likely inhibitkgtPexpression through binding to the -35 region ofkgtPpromoter and occluding the occupancy of RNA polymerases. Genec5038can be specifically induced by KG, whereas the expression ofkgtPdoes not respond to KG, yet can be stimulated during growth on glycerol. In addition,c5038andkgtPexpression were further shown to be controlled by different alternative sigma factors RpoN and RpoS, respectively. Furthermore, dual-strain competition assays in a murine model showed thatc5038mutant but notkgtPmutant was outcompeted by the wild-type strain during the colonization of murine bladders and kidneys, highlighting the importance of C5038 underin vivoconditions. Therefore, different transcriptional regulation led to distinct roles played by C5038 and KgtP in KG utilization and fitnessin vivo. This study thus potentially expanded our understanding of UPEC pathobiology.
authors.affiliation: Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China.
authors.forename: Wentong
authors.initials: W
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University Wuhan, China.
authors.forename: Xuwang
authors.initials: X
authors.lastname: Cai
authors.affiliation: Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China.
authors.forename: Yongwu
authors.initials: Y
authors.lastname: Yang
authors.affiliation: School of Bioengineering, Shandong Provincial Key Laboratory of Microbial Engineering, Qilu University of Technology Jinan, China.
authors.forename: Shigan
authors.initials: S
authors.lastname: Yan
authors.affiliation: Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Nanjing Agricultural UniversityNanjing, China; Department of Clinical Veterinary Science, College of Veterinary Medicine, Nanjing Agricultural UniversityNanjing, China.
authors.forename: Haibin
authors.initials: H
authors.lastname: Zhang
keywords: sigma factor; transcriptional regulation; transporter; uropathogenic Escherichia coli; α-ketoglutarate