The regulation of AsfR on tmRNA expression mediates bacterial motility and virulence in <i>aeromonas veronii</i>

Abstract

Transfer messenger RNA (tmRNA), a key component of the trans-translation system, plays an essential role on the virulence of pathogenic bacteria. However, the upstream regulatory mechanisms that regulate tmRNA expression remain largely unexplored. In this study, AraC superfamily regulator (AsfR) was found to directly interact with the promoter of <i>ssrA</i> gene, which encodes tmRNA. Co-transformation of the reporter construct, consisting of tmRNA promoter fused to enhanced green fluorescent protein (eGFP), alongside an AsfR expression vector, resulted in increased fluorescence, indicating that AsfR positively regulates mRNA expression. Consistently, the transcription level of tmRNA was significantly decreased in Δ<i>asfR</i> compared with WT of <i>A. veronii</i> by quantitative real-time PCR (RT-qPCR) analyses. The Δ<i>asfR</i> and Δ<i>tmRNA</i> mutants exhibited significantly reduced motility and biofilm formation. Reduced transcription of the flagellar gene <i>fliE</i> in both mutants suggests that the AsfR/tmRNA axis may regulate these processes via <i>fliE</i>. Futhermore, deletion of <i>asfR</i> and tmRNA impairs oxidant resistance and pathogenicity, resulting in growth inhibition in <i>A. veronii</i>. This study elucidates the regulatory role of the AsfR-tmRNA pathway in flagellar motility, biofilm formation, and antioxidant capacity, all of which contribute to bacterial virulence and provide potential targets for the treatment of bacterial infections.

Affiliated Institutions

• Hainan University CN
• Yunnan Agricultural University CN
• Chinese Academy of Agricultural Sciences CN
• Biotechnology Research Institute CN

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