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

Abstract

20Biofilms are multicellular bacterial communities encased in a self-secreted extracellular 21 matrix comprised of polysaccharides, proteinaceous fibers, and DNA. Organization of 22 these components lends spatial organization to the biofilm community such that biofilm 23 residents can benefit from the production of common goods, while being protected from 24 exogenous insults. Spatial organization is driven by the presence of chemical gradients, 25 such as oxygen. Here we quantified and localized the expression of two Escherichia coli 26 cytochrome oxidases in cells found in the biofilm state and defined their contribution to 27 biofilm architecture. These studies elucidated a role for the high-affinity quinol oxidase 28 cytochrome bd in matrix production and biofilm resident protection. Cytochrome bd was 29 the most abundantly expressed respiratory complex in the biofilm community and was 30 localized in the biofilm interior. Depletion of the cytochrome bd-expressing 31 subpopulation led to decreased extracellular matrix and increased sensitivity of the 32 community to exogenous stresses. Interrogation of the distribution of cytochrome 33 oxidases in the planktonic state revealed that ~15% of the population expresses 34 cytochrome bd at atmospheric oxygen concentration, and this population dominates 35 during acute urinary tract infection. These data point towards a bet-hedging mechanism 36 in which heterogeneous expression of respiratory complexes ensures respiratory 37 plasticity of E. coli across diverse host niches. 38 39 Keywords 40 biofilms, heterogeneity, oxygen gradients, respiration, urinary tract infection 41 Importance 42Biofilms are multicellular bacterial communities encased in a self-secreted extracellular 43 matrix comprised of polysaccharides, proteinaceous fibers, and DNA. Organization of 44 these components lends spatial organization in the biofilm community. Here we 45 demonstrate that oxygen gradients in uropathogenic Escherichia coli (UPEC) biofilms 46 lead to spatially distinct expression programs for cytochrome oxidases -components of 47 the terminal electron transport chain. Our studies reveal that the cytochrome bd-48 expressing subpopulation is critical for biofilm development and matrix production. In 49 addition, we show that cytochrome oxidases are also heterogeneously expressed in 50 planktonic populations, and that this respiratory heterogeneity provides a fitness 51 advantage during infection. These studies define the contributions of cytochrome 52 oxidases to biofilm physiology and suggest the presence of respiratory bet-hedging 53 behavior in UPEC. 54 55 Introduction 56Rather than existing as a phenotypically uniform population, bacterial 57 communities are characterized by subpopulations that are oftentimes phenotypically 58 distinct. This intra-strain heterogeneity can be transient, brought about by stochastic 59 differences in the abundance and activity of regulators in each individual cell, or it can 60 be irreversible, through the acquisition of mutations. Heterogeneity inf...

Balanced Input from the tRNA Prenyltransferase MiaA Controls the Stress Resistance and Virulence Potential of Extraintestinal PathogenicEscherichia coli

“…8). Interestingly, the biofilms formed by UTI89∆miaA were architecturally similar to those formed by a UTI89 mutant lacking the CyoC-interacting partners CyoAB [78].…”

“…Factors linked with biofilm development include YoaB, the type 1 pilus-associated regulator FimB and periplasmic chaperone FimC, the acid stressresponse chaperone HdeB, the cellulose synthase catalytic subunit BcsA, and the cytochrome bo subunit CyoC. Using yeast extract-casamino acids (YESCA) medium, which promotes the development of elaborate rugose-colony biofilms [77,78], we found that UTI89∆miaA, but not UTI89∆miaB, formed atypical biofilms with notably less rugosity than the parent strain (Fig. 8).…”

“…In vitro rugose biofilm assays were performed starting with cultures grown overnight at 37°C shaking in LB, as described [78]. Bacteria from each culture were then brought to an OD600 of ~1.0 and 10 µl aliquots were spotted onto YESCA agar plates (12 g/l Casamino acids, 1.2 g yeast extract, g agar) and incubated at RT (~20-22˚C).…”

Enzymatic and Non-Enzymatic Response during Nitrosative Stress in Escherichia coli

“…At the same time, it also helps E. coli cells to survive inside macrophages. This enzyme also plays a vital role in biofilm formation, where transcriptomic data showed the upregulation of cydABX in mature UPEC biofilms [8,42]. However, a high concentration of NO• renders it inactive [90].…”

Ammonium chloride‐induced acidosis exacerbates cystitis and pyelonephritis caused by uropathogenicE. coli

“…Induction of NOS2 (inducible Nitric Oxide Synthase, iNOS) leading to increased production of nitric oxide (NO) and reactive nitric oxide species (RNOS; nitrosative stress) is a key component of the TLR4‐dependent innate immune response to gram‐negative bacteria (Bogdan, 2015; Schairer et al, 2012). Thus, UPEC possess a metabolic program that promotes survival in acidified urine via amino acid metabolism, polyamines synthesis and transport, and detoxification of nitric oxide (Beebout et al, 2019; Beebout et al, 2021; Mason et al, 2009; Soksawatmaekhin et al, 2004).…”