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The involvement of CiaR and the CiaR-regulated serine protease HtrA in thermal adaptation of Streptococcus pneumoniae.

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posted on 2023-07-06, 14:40 authored by Ozcan Gazioglu, Medhanie Habtom, Peter W Andrew, Hasan Yesilkaya
The in vivo temperature can vary according to the host tissue and the response to infection. Streptococcus pneumoniae has evolved mechanisms to survive these temperature differences, but neither the consequences of different temperatures for pneumococcal phenotype nor the genetic basis of thermal adaptation are known in detail. In our previous study [16], we found that CiaR, which is a part of two-component regulatory system CiaRH, as well as 17 genes known to be controlled by CiaRH, were identified to be differentially expressed with temperature. One of the CiaRH-regulated genes shown to be differentially regulated by temperature is for the high-temperature requirement protein (HtrA), coded by SPD_2068 (htrA). In this study, we hypothesized that the CiaRH system plays an important role in pneumococcal thermal adaptation through its control over htrA. This hypothesis was evaluated by testing strains mutated or overexpressing ciaR and/or htrA, in in vitro and in vivo assays. The results showed that in the absence of ciaR, the growth, haemolytic activity, amount of capsule and biofilm formation were considerably diminished at 40 °C only, while the cell size and virulence were affected at both 34 and 40 °C. The overexpression of htrA in the ∆ciaR background reconstituted the growth at all temperatures, and the haemolytic activity, biofilm formation and virulence of ∆ciaR partially at 40 °C. We also showed that overexpression of htrA in the wild-type promoted pneumococcal virulence at 40 °C, while the increase of capsule was observed at 34 °C, suggesting that the role of htrA changes at different temperatures. Our data suggest that CiaR and HtrA play an important role in pneumococcal thermal adaptation.

Funding

H.Y. is grateful for support from the NIH (R01 AI139077-01A1 and 411 R01 AI135060-01A1).

History

Citation

Gazioglu O, Habtom M, Andrew PW, Yesilkaya H. The involvement of CiaR and the CiaR-regulated serine protease HtrA in thermal adaptation of Streptococcus pneumoniae. Microbiology (Reading). 2023 Feb;169(2):001304. doi: 10.1099/mic.0.001304. PMID: 36811449; PMCID: PMC10197876.

Author affiliation

Department of Respiratory Sciences, University of Leicester

Published in

Microbiology (Reading, England)

Volume

169

Issue

2

Publisher

Microbiology Society

issn

1350-0872

eissn

1465-2080

Acceptance date

2022-02-03

Copyright date

2022

Available date

2023-07-06

Spatial coverage

England

Language

eng

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