Biology subjects

Brannon, J. R.

Publications and source records attributed to Brannon, J. R..

2 recordsLinked to original sources

bioRxiv2019

Identification and characterization of OmpT-like proteases in uropathogenic Escherichia coli clinical isolates

Bacterial colonization of the urogenital tract is limited by innate defenses, including the production of antimicrobial peptides (AMPs). Uropathogenic Escherichia coli (UPEC) resist AMP-killing to cause a range of urinary tract infections (UTIs) including asymptomatic bacteriuria, cystitis, pyelonephritis, and sepsis. UPEC strains have high genomic diversity and encode numerous virulence factors that differentiate them from non-UTI causing strains, including ompT. As OmpT homologues cleave and inactivate AMPs, we hypothesized that high OmpT protease activity-levels contribute to UPEC colonization during symptomatic UTIs. Therefore, we measured OmpT activity in 58 UPEC clinical isolates. While heterogeneous OmpT activities were observed, OmpT activity was significantly greater in UPEC strains isolated from patients with symptomatic infections. Unexpectedly, UPEC strains exhibiting the greatest protease activities harboured an additional ompT-like gene called arlC (ompTp). The presence of two OmpT-like proteases in some UPEC isolates led us to compare the substrate specificities of OmpT-like proteases found in E. coli. While all three cleaved AMPs, cleavage efficiency varied on the basis of AMP size and secondary structure. Our findings suggest the presence ArlC and OmpT in the same UPEC isolate may confer a fitness advantage by expanding the range of target substrates.

microbiology↗

bioRxiv2018

Respiratory heterogeneity shapes biofilm formation and host colonization in uropathogenic Escherichia coli

Biofilms are multicellular bacterial communities encased in a self-secreted extracellular matrix comprised of polysaccharides, proteinaceous fibers, and DNA. Organization of these components lends spatial organization to the biofilm community such that biofilm residents can benefit from the production of common goods, while being protected from exogenous insults. Spatial organization is driven by the presence of chemical gradients, such as oxygen. Here we quantified and localized the expression of two Escherichia coli cytochrome oxidases in cells found in the biofilm state and defined their contribution to biofilm architecture. These studies elucidated a role for the high-affinity quinol oxidase cytochrome bd in matrix production and biofilm resident protection. Cytochrome bd was the most abundantly expressed respiratory complex in the biofilm community and was localized in the biofilm interior. Depletion of the cytochrome bd-expressing subpopulation led to decreased extracellular matrix and increased sensitivity of the community to exogenous stresses. Interrogation of the distribution of cytochrome oxidases in the planktonic state revealed that [~]15% of the population expresses cytochrome bd at atmospheric oxygen concentration, and this population dominates during acute urinary tract infection. These data point towards a bet-hedging mechanism in which heterogeneous expression of respiratory complexes ensures respiratory plasticity of E. coli across diverse host niches.

microbiology↗