Inactivation of thyA in Staphylococcus aureus Attenuates Virulence and Has a Strong Impact on Metabolism and Virulence Gene Expression

Media type: E-Article
Title: Inactivation of thyA in Staphylococcus aureus Attenuates Virulence and Has a Strong Impact on Metabolism and Virulence Gene Expression
Contributor: Kriegeskorte, Andre; Block, Desiree; Drescher, Mike; Windmüller, Nadine; Mellmann, Alexander; Baum, Cathrin; Neumann, Claudia; Lorè, Nicola Ivan; Bragonzi, Alessandra; Liebau, Eva; Hertel, Patrick; Seggewiss, Jochen; Becker, Karsten; Proctor, Richard A.; Peters, Georg; Kahl, Barbara C.
imprint: American Society for Microbiology, 2014
Published in: mBio, 5 (2014) 4
Language: English
DOI: 10.1128/mbio.01447-14
ISSN: 2150-7511; 2161-2129
Origination:
Footnote:
Description: <jats:title>ABSTRACT</jats:title> <jats:p> <jats:named-content content-type="genus-species">Staphylococcus aureus</jats:named-content> thymidine-dependent small-colony variants (TD-SCVs) are frequently isolated from patients with chronic <jats:named-content content-type="genus-species">S. aureus</jats:named-content> infections after long-term treatment with trimethoprim-sulfamethoxazole (TMP-SMX). While it has been shown that TD-SCVs were associated with mutations in thymidylate synthase (TS; <jats:italic>thyA</jats:italic> ), the impact of such mutations on protein function is lacking. In this study, we showed that mutations in <jats:italic>thyA</jats:italic> were leading to inactivity of TS proteins, and TS inactivity led to tremendous impact on <jats:named-content content-type="genus-species">S. aureus</jats:named-content> physiology and virulence. Whole DNA microarray analysis of the constructed Δ <jats:italic>thyA</jats:italic> mutant identified severe alterations compared to the wild type. Important virulence regulators ( <jats:italic>agr</jats:italic> , <jats:italic>arlRS</jats:italic> , <jats:italic>sarA</jats:italic> ) and major virulence determinants ( <jats:italic>hla</jats:italic> , <jats:italic>hlb</jats:italic> , <jats:italic>sspAB</jats:italic> , and <jats:italic>geh</jats:italic> ) were downregulated, while genes important for colonization ( <jats:italic>fnbA</jats:italic> , <jats:italic>fnbB</jats:italic> , <jats:italic>spa</jats:italic> , <jats:italic>clfB</jats:italic> , <jats:italic>sdrC</jats:italic> , and <jats:italic>sdrD</jats:italic> ) were upregulated. The expression of genes involved in pyrimidine and purine metabolism and nucleotide interconversion changed significantly. NupC was identified as a major nucleoside transporter, which supported growth of the mutant during TMP-SMX exposure by uptake of extracellular thymidine. The Δ <jats:italic>thyA</jats:italic> mutant was strongly attenuated in virulence models, including a <jats:named-content content-type="genus-species">Caenorhabditis elegans</jats:named-content> killing model and an acute pneumonia mouse model. This study identified inactivation of TS as the molecular basis of clinical TD-SCV and showed that <jats:italic>thyA</jats:italic> activity has a major role for <jats:named-content content-type="genus-species">S. aureus</jats:named-content> virulence and physiology. </jats:p> <jats:p> <jats:bold>IMPORTANCE</jats:bold> Thymidine-dependent small-colony variants (TD-SCVs) of <jats:named-content content-type="genus-species">Staphylococcus aureus</jats:named-content> carry mutations in the thymidylate synthase (TS) gene ( <jats:italic>thyA</jats:italic> ) responsible for <jats:italic>de novo</jats:italic> synthesis of thymidylate, which is essential for DNA synthesis. TD-SCVs have been isolated from patients treated for long periods with trimethoprim-sulfamethoxazole (TMP-SMX) and are associated with chronic and recurrent infections. In the era of community-associated methicillin-resistant <jats:named-content content-type="genus-species">S. aureus</jats:named-content> , the therapeutic use of TMP-SMX is increasing. Today, the emergence of TD-SCVs is still underestimated due to misidentification in the diagnostic laboratory. This study showed for the first time that mutational inactivation of TS is the molecular basis for the TD-SCV phenotype and that TS inactivation has a strong impact on <jats:named-content content-type="genus-species">S. aureus</jats:named-content> virulence and physiology. Our study helps to understand the clinical nature of TD-SCVs, which emerge frequently once patients are treated with TMP-SMX. </jats:p>
Access State: Open Access

Search in field:

Recently searched for: