Biology subjects

Kwiecinski, J.

Publications and source records attributed to Kwiecinski, J..

3 recordsLinked to original sources

bioRxiv2022

Host-derived protease promotes aggregation of Staphylococcus aureus by cleaving the surface protein SasG

Staphylococcus aureus is one of the leading causes of hospital acquired infections, many of which begin following attachment and accumulation on indwelling medical devices or diseased tissue. These infections are often linked to establishment of biofilms, but another often overlooked key characteristic allowing S. aureus to establish persistent infection is formation of planktonic aggregates. Such aggregates are physiologically similar to biofilms and protect pathogen from innate immune clearance and increase its antibiotic tolerance. The cell wall-associated protein SasG has been implicated in biofilm formation via mechanisms of intercellular aggregation, but the mechanism in the context of disease is largely unknown. We have previously shown that expression of cell wall-anchored proteins involved in biofilm formation is controlled by the ArlRS-MgrA regulatory cascade. In this work, we demonstrate that the ArlRS two-component system controls aggregation, by repressing expression of sasG by activation of the global regulator MgrA. We also demonstrate that SasG must be proteolytically processed by a non-native protease to induce aggregation, and that strains expressing functional full-length sasG aggregate significantly upon proteolysis by a mucosal-derived host protease found in human saliva. We used fractionation and N-terminal sequencing to demonstrate that human trypsin within saliva cleaves within the A domain of SasG to expose the B domain and induce aggregation. Finally, we demonstrated that SasG is involved in virulence during mouse lung infection. Together, our data point to SasG, its processing by host proteases, and SasG-driven aggregation as important elements of S. aureus adaptation to host environment.

microbiology↗

bioRxiv2020

MgrA regulates interaction of Staphylococcus aureus with mucin

BackgroundTo defend the lungs, mucus adheres to bacterial cells and facilitates their removal by ciliary transport. Our goals were to measure the affinity of mucus for the respiratory pathogen Staphylococcus aureus and identify bacterial genes that regulate this interaction. MethodsS. aureus was added to pig tracheas to determine whether it binds mucus or epithelial cells. To quantify its affinity for mucus, we developed a competition assay in microtiter plates. Mucin was added over a dose range as an inhibitor of bacterial attachment. We then examined how transcriptional regulator MgrA and cell wall transpeptidase sortase (SrtA) affect bacterial interaction with mucin. ResultsIn pig tracheas, S. aureus bound mucus strands from submucosal glands more than epithelial cells. In microtiter plate assays, {Delta}srtA failed to attach even in the absence of mucin. Mucin blocked wild type S. aureus attachment in a dose-dependent manner. Higher concentrations were needed to inhibit binding of {Delta}mgrA. Co-deletion of ebh and sraP, which encode surface proteins repressed by MgrA, suppressed the {Delta}mgrA binding phenotype. No differences between {Delta}mgrA and wild type were observed when methylcellulose or heparin sulfate were substituted for mucin, indicating specificity. ConclusionsMucin decreases attachment of S. aureus to plastic, consistent with its physiologic role in host defense. S. aureus deficient in MgrA has decreased affinity for mucin. Ebh and SraP, which are normally repressed by MgrA, may function as inhibitors of attachment to mucin. These data show that specific bacterial factors may regulate the interaction of S. aureus with mucus.

microbiology↗

bioRxiv2019

Identification of key determinants of Staphylococcus aureus vaginal colonization

Staphylococcus aureus is an important pathogen responsible for nosocomial and community acquired infections in humans, and methicillin-resistant S. aureus (MRSA) infections have continued to increase despite wide-spread preventative measures. S. aureus can colonize the female vaginal tract and reports have suggested an increase in MRSA infections in pregnant and postpartum women as well as outbreaks in newborn nurseries. Currently, little is known about specific factors that promote MRSA vaginal colonization and subsequent infection. To study S. aureus colonization of the female reproductive tract in a mammalian system, we developed a mouse model of S. aureus vaginal carriage and demonstrated that both hospital-associated and community-associated MRSA isolates can colonize the murine vaginal tract. Immunohistochemical analysis revealed an increase in neutrophils in the vaginal lumen during MRSA colonization. Additionally, we observed that a mutant lacking fibrinogen binding adhesins exhibited decreased persistence within the mouse vagina. To further identify novel factors that promote vaginal colonization, we performed RNA-sequencing to determine the transcriptome of MRSA growing in vivo during vaginal carriage at 5 hours, 1-day, and 3-days post-inoculation. Over 25% of bacterial genes were differentially regulated at all time points during colonization compared to laboratory cultures. The most highly induced genes were those involved in iron acquisition, including the Isd system and siderophore transport systems. Mutants deficient in these pathways did not persist as well during in vivo colonization. These results reveal that fibrinogen binding as well as the capacity to overcome host nutritional limitation are important determinants of MRSA vaginal colonization.\n\nIMPORTANCEStaphylococcus aureus is an opportunistic pathogen able to cause a wide variety of infections in humans. Recent reports have suggested an increasing prevalence of MRSA in pregnant and postpartum women, coinciding with the increased incidence of MRSA infections in the NICU and newborn nurseries. Vertical transmission from mothers to infants at delivery is a likely route of MRSA acquisition by the newborn, however, essentially nothing is known about host and bacterial factors that influence MRSA carriage in the vagina. Here, we established a mouse model of vaginal colonization and observed that multiple MRSA strains can persist in the vaginal tract. Additionally, we determined that MRSA interactions with fibrinogen as well as iron uptake can promote vaginal persistence. This study is the first to identify molecular mechanisms which govern vaginal colonization by MRSA, the critical initial step preceding infection and neonatal transmission.

microbiology↗