<abstract xmlns="http://www.w3.org/1999/xhtml">

<p><italic>Serratia marcescens</italic> is a global opportunistic pathogen. <italic>In vitro</italic> cytotoxicity of this bacterium is mainly related to metalloprotease serralysin (PrtS) activity. Proteolytic capability varies among the different isolates. Here, we characterized protease production and transcriptional regulators at 37°C of two <italic>S. marcescens</italic> isolates from bronchial expectorations, HU1848 and SmUNAM836. As a reference strain the insect pathogen <italic>S. marcescens</italic> Db10 was included. Zymography of supernatant cultures revealed a single (SmUNAM836) or double proteolytic zones (HU1848 and Db10). Mass spectrometry confirmed the identity of PrtS and the serralysin-like protease SlpB from supernatant samples. Elevated proteolytic activity and <italic>prtS</italic> expression were evidenced in the HU1848 strain through azocasein degradation and qRT-PCR, respectively. Evaluation of transcriptional regulators revealed higher <italic>eepR</italic> expression in HU1848, whereas <italic>cpxR</italic> and <italic>hexS</italic> transcriptional levels were similar between studied strains. Higher <italic>eepR</italic> expression in HU1848 was further confirmed through an <italic>in vivo</italic> transcriptional assay. Moreover, two putative CpxR binding motifs were identified within the <italic>eepR</italic> regulatory region. EMSA validated the interaction of CpxR with both motifs. The evaluation of <italic>eepR</italic> transcription in a <italic>cpxR</italic> deletion strain indicated that CpxR negatively regulates <italic>eepR</italic>. Sequence conservation suggests that regulation of <italic>eepR</italic> by CpxR is common along <italic>S. marcescens</italic> species. Overall, our data incorporates CpxR to the complex regulatory mechanisms governing <italic>eepR</italic> expression and associates the increased proteolytic activity of the HU1848 strain with higher <italic>eepR</italic> transcription. Based on the global impact of EepR in secondary metabolites production, our work contributes to understanding virulence factors variances across <italic>S. marcescens</italic> isolates.</p>
</abstract>

Serratia marcescens is a global opportunistic pathogen. In vitro cytotoxicity of this bacterium is mainly related to metalloprotease serralysin (PrtS) activity. Proteolytic capability varies among the different isolates. Here, we characterized protease production and transcriptional regulators at 37°C of two S. marcescens isolates from bronchial expectorations, HU1848 and SmUNAM836. As a reference strain the insect pathogen S. marcescens Db10 was included. Zymography of supernatant cultures revealed a single (SmUNAM836) or double proteolytic zones (HU1848 and Db10). Mass spectrometry confirmed the identity of PrtS and the serralysin-like protease SlpB from supernatant samples. Elevated proteolytic activity and prtS expression were evidenced in the HU1848 strain through azocasein degradation and qRT-PCR, respectively. Evaluation of transcriptional regulators revealed higher eepR expression in HU1848, whereas cpxR and hexS transcriptional levels were similar between studied strains. Higher eepR expression in HU1848 was further confirmed through an in vivo transcriptional assay. Moreover, two putative CpxR binding motifs were identified within the eepR regulatory region. EMSA validated the interaction of CpxR with both motifs. The evaluation of eepR transcription in a cpxR deletion strain indicated that CpxR negatively regulates eepR. Sequence conservation suggests that regulation of eepR by CpxR is common along S. marcescens species. Overall, our data incorporates CpxR to the complex regulatory mechanisms governing eepR expression and associates the increased proteolytic activity of the HU1848 strain with higher eepR transcription. Based on the global impact of EepR in secondary metabolites production, our work contributes to understanding virulence factors variances across S. marcescens isolates.

Increased Proteolytic Activity of <italic>Serratia marcescens</italic> Clinical Isolate HU1848 Is Associated with Higher <italic>eepR</italic> Expression

Polish Journal of Microbiology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Increased Proteolytic Activity of  Clinical Isolate HU1848 Is Associated with Higher  Expression

Serratia marcescens is a global opportunistic pathogen. In vitro cytotoxicity of this bacterium is mainly related to metalloprotease serralysin (PrtS)...

Increased Proteolytic Activity of Serratia marcescens Clinical Isolate HU1848 Is Associated with Higher eepR Expression

Article Category: ORIGINAL PAPER

Publicado en línea: 04 mar 2024

Páginas: 11 - 20

Recibido: 22 sept 2023

Aceptado: 14 dic 2023

DOI: https://doi.org/10.33073/pjm-2024-002

Palabras clave
serralysin, protease, EepR, CpxR

© 2024 Karla L. De Anda-Mora et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Increased Proteolytic Activity of Serratia marcescens Clinical Isolate HU1848 Is Associated with Higher eepR Expression

Article Category: ORIGINAL PAPER

Publicado en línea: 04 mar 2024

Páginas: 11 - 20

Recibido: 22 sept 2023

Aceptado: 14 dic 2023

DOI: https://doi.org/10.33073/pjm-2024-002

Palabras claveserralysin, protease, EepR, CpxR

© 2024 Karla L. De Anda-Mora et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Palabras clave
serralysin, protease, EepR, CpxR