Biology subjects

Rowley, D. C.

Publications and source records attributed to Rowley, D. C..

5 recordsLinked to original sources

bioRxiv2023

Metabolic flux regulates growth transitions and antibiotic tolerance in uropathogenic Escherichia coli

Reducing growth and limiting metabolism are strategies that allow bacteria to survive exposure to environmental stress and antibiotics. During infection, uropathogenic Escherichia coli (UPEC) may enter a quiescent state that enables them to reemerge after completion of successful antibiotic treatment. Many clinical isolates, including the well characterized UPEC strain CFT073, also enter a metabolite-dependent, quiescent state in vitro that is reversible with cues, including peptidoglycan-derived peptides and amino acids. Here, we show that quiescent UPEC is antibiotic tolerant and demonstrate that metabolic flux in the tricarboxylic acid (TCA) cycle regulates the UPEC quiescent state via succinyl-CoA. We also demonstrate that the transcriptional regulator complex IHF and the FtsZ-interacting protein ZapE, which is important for E. coli division during stress, are essential for UPEC to enter the quiescent state. Notably, in addition to engaging FtsZ and late-stage cell division proteins, ZapE also interacts directly with TCA cycle enzymes in bacterial two hybrid assays. We report direct interactions between succinate dehydrogenase complex subunit SdhC, the late-stage cell division protein FtsN, and ZapE. These interactions likely enable communication between oxidative metabolism and the cell division machinery in UPEC. Moreover, these interactions are conserved in an E. coli K-12 strain. This work suggests that there is coordination among the two fundamental and essential pathways that regulate overall growth, quiescence, and antibiotic susceptibility. ImportanceUropathogenic Escherichia coli (UPEC) are the leading cause of urinary tract infections (UTIs). Upon invasion into bladder epithelial cells, UPEC establish quiescent intracellular reservoirs that may lead to antibiotic tolerance and recurrent UTIs. Here, we demonstrate using an in vitro system that quiescent UPEC cells are tolerant to ampicillin and have decreased metabolism characterized by succinyl-CoA limitation. We identify the global regulator the IHF complex and the cell division protein ZapE as critical regulators of quiescence and antibiotic tolerance. Lastly, we show ZapE interacts with components of both the cell division machinery and the TCA cycle, and this interaction is conserved in non-pathogenic E. coli, establishing a novel link between cell division and metabolism.

cell biology↗

bioRxiv2022

Development and evaluation of a formulation of probiont Phaeobacter inhibens S4 for themanagement of vibriosis in bivalve hatcheries

Larval eastern oysters (Crassostrea virginica) grown in shellfish hatcheries are susceptible to bacterial diseases, particularly vibriosis. Probiotics are microbes that confer health benefits to the host and have been identified as promising tools to manage diseases in aquaculture. The marine bacterium Phaeobacter inhibens S4 (S4) protects larval eastern oysters against challenge with the bacterial pathogen Vibrio coralliilyticus RE22 (RE22). A concentrated liquid formulation of probiont S4 that maintained high cell viability after long-term storage was developed for commercial use in shellfish hatcheries. The safety and efficacy of the formulation was tested in six different trials in two hatcheries. The S4 formulation was added to C. virginica larvae culture tanks daily at 104 colony forming units (CFU)/mL from day 1 post fertilization until day 6, 12, or 14, depending on the trial. Treatment of larvae in the hatchery with the S4 formulation did not significantly affect the survival and growth of the larvae. Formulated probiont S4 treatment in the hatchery led to a significant increase in Relative Percent Survival (RPS) when larvae were subsequently challenged with the pathogen RE22 (105 CFU/mL) for 24 hours in a laboratory challenge, as compared to probiotic-untreated RE22-challenged larvae (Relative Percent Survival increase of 46 - 74%, p < 0.05). These results suggest that this novel S4 formulation is a safe, easy to use, and effective tool in preventing larval losses due to vibriosis in hatcheries.

microbiology↗

bioRxiv2022

Screening the PRISM library against Staphylococcus aureus reveals a sesquiterpene lactone from Liriodendron tulipifera with inhibitory activity

Infections caused by the bacterium Staphylococcus aureus continue to pose threats to human health and put a financial burden on the healthcare system. The overuse of antibiotics has contributed to mutations leading to the emergence of methicillin-resistant Staphylococcus aureus, and there is a critical need for the discovery and development of new antibiotics to evade drug resistant bacteria. Medicinal plants have shown promise as sources of new small molecule therapeutics with potential uses against pathogenic infections. The Principal Rhode Island Secondary Metabolite (PRISM) library is a botanical extract library generated from specimens in the URI Heber W. Youngken Jr. Medicinal Garden by upper-division undergraduate students. PRISM extracts were screened for activity against strains of methicillin-susceptible S. aureus (MSSA). An extract generated from the tulip tree (Liriodendron tulipifera) demonstrated growth inhibition against MSSA, and a bioassay-guided approach identified a sesquiterpene lactone, laurenobiolide, as the active constituent. Intriguingly, its isomers tulipinolide and epi-tulipinolide lacked potent activity against MSSA. Laurenobiolide also proved to be more potent against MSSA than the structurally similar sesquiterpene lactones constunolide and dehydrocostus lactone. Laurenobioloide was most abundant in the twig bark of the tulip tree, supporting the historical and cultural usage of twig bark in poultices and teas. ABSTRACT GRAPHIC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC="FIGDIR/small/494747v1_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@952221org.highwire.dtl.DTLVardef@f3a5daorg.highwire.dtl.DTLVardef@d91daorg.highwire.dtl.DTLVardef@e2a845_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2021

Two Type VI Secretion Systems in Vibrio coralliilyticus RE22Sm exhibit differential target specificity for bacteria prey and oyster larvae

Vibrio coralliilyticus is an extracellular bacterial pathogen and a causative agent of vibriosis in larval oysters. Host mortality rates can quickly reach 100% during vibriosis outbreaks in oyster hatcheries. Type VI Secretion Systems (T6SS) are rapidly polymerizing, contact dependent injection apparatus for prey cell intoxication and play important roles in pathogenesis. DNA sequencing of V. coralliilyticus RE22Sm indicated the likely presence of two functional T6SSs with one on each of two chromosomes. Here, we investigated the antibacterial and anti-eukaryotic roles of the two T6SSs (T6SS1 and T6SS2) against E. coli Sm10 cells and Crassostrea virginica larvae, respectively. Mutations in hcp and vgrG genes were created and characterized for their effects upon bacterial antagonism and eukaryotic host virulence. Mutations in hcp1 and hcp2 resulted in significantly reduced antagonism against E. coli Sm10, with the hcp2 mutation demonstrating the greater impact. In contrast, mutations in vgrG1 or vgrG2 had little effect on E. coli killing. In eastern oyster larval challenge assays, T6SS1 mutations in either hcp1 or vgrG1 dramatically attenuated virulence against C. virginica larvae. Strains with restored wild type hcp or vgrG genes reestablished T6SS-mediated killing to that of wild type V. coralliilyticus RE22Sm. These data suggest that the T6SS1 of V. coralliilyticus RE22Sm principally targets eukaryotes and secondarily bacteria, while the T6SS2 primarily targets bacterial cells and secondarily eukaryotes. Attenuation of pathogenicity was observed in all T6SS mutants, demonstrating the requirement for proper assembly of the T6SS systems to maintain maximal virulence. ImportanceVibriosis outbreaks lead to large-scale hatchery losses of oyster larvae (product and seed) where Vibrio sp. associated losses of 80 to 100 percent are not uncommon. Practical and proactive biocontrol measures can be taken to help mitigate larval death by Vibrio sp. by better understanding the underlying mechanisms of virulence in V. coralliilyticus. In this study, we demonstrate the presence of two Type VI Secretion Systems (T6SS) in V. coralliilyticus RE22Sm and interrogate the roles of each T6SS in bacterial antagonism and pathogenesis against a eukaryotic host. Specifically, we show that the loss of T6SS1 function results in the loss of virulence against oyster larvae.

microbiology↗

bioRxiv2019

Peptidoglycan sensing prevents quiescence and promotes quorum-independent growth of uropathogenic Escherichia coli

The layer of peptidoglycan surrounding bacteria provides structural integrity for the bacterial cell wall. Many organisms, including human cells and diverse bacteria, detect peptidoglycan fragments that are released as bacteria grow. Uropathogenic Escherichia coli (UPEC) strains are the leading cause of human urinary tract infections (UTIs) and many patients experience recurrent infection after successful antibiotic treatment. The source of recurrent infections may be persistent bacterial reservoirs in vivo that are in a quiescent state and, thus, are not susceptible to antibiotics. Here, we show that multiple UPEC strains require a quorum to proliferate in vitro with glucose as the sole carbon source; at low density, the bacteria remain viable but enter a quiescent, non-proliferative state. Of all clinical UPEC isolates tested to date, 35% (51/145) enter this quiescent state, including archetypal strains CFT073 (from classic endemic lineage ST73) and JJ1886 (from recently emerged, multidrug-resistant pandemic lineage ST131). We further show that quorum-dependent UPEC quiescence is prevented and reversed by small molecules, called proliferants, that stimulate growth, such as L-lysine, L-methionine, and peptidoglycan (PG) stem peptides, including an isolated PG pentapeptide from Staphylococcus aureus. Together, our results indicate that (i) uptake of L-lysine and (ii) PG peptide sensing by UPEC modulate the quorum-regulated decision to proliferate and further demonstrate that PG fragments are important for intra- and interspecies signaling in pathogenic E. coli.

microbiology↗