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Thermosensitive pilus production by FCT type 3 Streptococcus pyogenes controlled by Nra regulator translational efficiency.

Authors
  • Nakata, Masanobu1
  • Sumitomo, Tomoko1
  • Patenge, Nadja2
  • Kreikemeyer, Bernd2
  • Kawabata, Shigetada1
  • 1 Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka, 565-0871, Japan. , (Japan)
  • 2 Institute of Medical Microbiology, Virology and Hygiene, University of Rostock, Rostock, D-18057, Germany. , (Germany)
Type
Published Article
Journal
Molecular Microbiology
Publisher
Wiley (Blackwell Publishing)
Publication Date
Jan 01, 2020
Volume
113
Issue
1
Pages
173–189
Identifiers
DOI: 10.1111/mmi.14408
PMID: 31633834
Source
Medline
Language
English
License
Unknown

Abstract

Streptococcus pyogenes produces a diverse variety of pili in a serotype-dependent manner and thermosensitive expression of pilus biogenesis genes was previously observed in a serotype M49 strain. However, the precise mechanism and biological significance remain unclear. Herein, the pilus expression analysis revealed the thermosensitive pilus production only in strains possessing the transcriptional regulator Nra. Experimental data obtained for nra deletion and conditional nra-expressing strains in the background of an M49 strain and the Lactococcus heterologous expression system, indicated that Nra is a positive regulator of pilus genes and also highlighted the importance of the level of intracellular Nra for the thermoregulation of pilus expression. While the nra mRNA level was not significantly influenced by a temperature shift, the Nra protein level was concomitantly increased when the culture temperature was decreased. Intriguingly, a putative stem-loop structure within the coding region of nra mRNA was a factor related to the post-transcriptional efficiency of nra mRNA translation. Either deletion of the stem-loop structure or introduction of silent chromosomal mutations designed to melt the structure attenuated Nra levels, resulting in decreased pilus production. Consequently, the temperature-dependent translational efficacy of nra mRNA influenced pilus thermoregulation, thereby potentially contributing to the fitness of nra-positive S. pyogenes in human tissues. © 2019 John Wiley & Sons Ltd.

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