Project description:More than half of women will experience a urinary tract infection (UTI) with uropathogenic Escherichia coli (UPEC) causing ~80% of uncomplicated cases. Iron acquisition systems are essential for uropathogenesis, and UPEC encode functionally redundant iron acquisition systems, underlining their importance. However, a recent UPEC clinical isolate, HM7 lacks this functional redundancy and instead encodes a sole siderophore, enterobactin. To determine if E. coli HM7 possesses unidentified iron acquisition systems, we performed RNA-sequencing under iron-limiting conditions and demonstrated the ferric citrate uptake system (fecABCDE and fecIR) was highly upregulated. Importantly, there are high levels of citrate within urine, some of which is bound to iron, and the fec system is highly enriched in UPEC isolates compared to commensal or fecal strains. Therefore, we hypothesized that HM7 and other similar strains use the fec system to acquire iron in the host. Deletion of both enterobactin biosynthesis and ferric citrate uptake (ΔentB/ΔfecA) abrogates use of ferric citrate as an iron source and fecA provides an advantage in pooled human urine in absence of enterobactin. However, in a UTI mouse model, fecA is a fitness factor independent of enterobactin production, likely due to the action of host Lipocalin-2 chelating ferrienterobactin. These findings indicate that ferric citrate uptake is used as an iron source when siderophore efficacy is limited, such as in the host during UTI. Defining these novel compensatory mechanisms and understanding the nutritional hierarchy of preferred iron sources within the urinary tract are important in the search for new approaches to combat UTI.
Project description:Urinary tract infections (UTIs) are a very common bacterial infectious disease in humans, and uropathogenic Escherichia coli (UPEC) are the most frequent cause of UTIs. During infection, UPEC must cope with a variety of stressful conditions in the urinary tract. Here, we demonstrated that the small RNA (sRNA) RyfA of UPEC strains was required for resistance to oxidative and osmotic stresses. Inactivation of ryfA in UPEC strain CFT073 decreased urinary tract colonization in CBA/J mice and the ryfA mutant also had reduced production of type 1 and P fimbriae, which are known to be important for UTI. Transcriptomic analysis of the ryfA mutant showed changes in expression of genes associated with general stress responses, metabolism, biofilm formation and genes coding for cell surface proteins. Furthermore, loss of ryfA also reduced UPEC survival in human macrophages. Thus, ryfA plays a key regulatory role in UPEC adaptation to stress, that contributes to UTI and survival in macrophages.
Project description:Strains of urinary tract associated E. coli both recent isolates and from the ECOR collection and non pathogenic E. coli strains were analyzed. Replicates were performed to establish the reproduciblity, then single experiments were performed there on.
Project description:Uropathogenic Escherichia coli utilize a variety of adherence factors that assist in colonization of the host urinary tract. TosA (type one secretion) is a non-fimbrial adhesin that is predominately expressed during murine urinary tract infection (UTI), binds to kidney epithelial cells, and promotes survival during invasive infections. The tosRCBDAEF operon encodes the secretory machinery necessary for TosA localization to the E. coli cell surface, as well as the transcriptional regulator TosR. TosR binds upstream of the tos operon and, in a concentration dependent manner, either induces or represses tosA expression. TosR is a member of the PapB family of fimbrial regulators that can participate in crosstalk between fimbrial operons. TosR also binds upstream of the pap operon and suppresses PapA production. However, the scope of TosR-mediated crosstalk is understudied and may be underestimated. To quantify the global effects of TosR-mediated regulation on the E. coli CFT073 genome, we induced expression of tosR, collected mRNA, and performed RNA-Seq. These findings show that production of TosR affected the expression of genes involved with adhesins, including P, F1C, and Auf; nitrate/nitrite transport; microcin secretion; and promoted biofilm formation.