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Plasmid pPCP1-derived sRNA HmsA promotes biofilm formation of Yersinia pestis
Zizhong Liu1,2, Xiaofang Gao1,3, Hongduo Wang1,4
1State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No. 20, Dongdajie, Fengtai, Beijing, 100071, China.
Background:
The ability of Yersinia pestis to form a biofilm is an important characteristic in flea transmission of this pathogen. Y. pestis laterally acquired two plasmids (pPCP1and pMT1) and the ability to form biofilms when it evolved from Yersinia pseudotuberculosis. Small regulatory RNAs (sRNAs) are thought to play a crucial role in the processes of biofilm formation and pathogenesis.
Results:
A pPCP1-derived sRNA HmsA (also known as sR084) was found to contribute to the enhanced biofilm formation phenotype of Y. pestis. The concentration of c-di-GMP was significantly reduced upon deletion of the hmsA gene in Y. pestis. The abundance of mRNA transcripts determining exopolysaccharide production, crucial for biofilm formation, was measured by primer extension, RT-PCR and lacZ transcriptional fusion assays in the wild-type and hmsA mutant strains. HmsA positively regulated biofilm synthesis-associated genes (hmsHFRS, hmsT and hmsCDE), but had no regulatory effect on the biofilm degradation-associated gene hmsP. Interestingly, the recently identified biofilm activator sRNA, HmsB, was rapidly degraded in the hmsA deletion mutant. Two genes (rovM and rovA) functioning as biofilm regulators were also found to be regulated by HmsA, whose regulatory effects were consistent with the HmsA-mediated biofilm phenotype.
Conclusion:
HmsA potentially functions as an activator of biofilm formation in Y. pestis, implying that sRNAs encoded on the laterally acquired plasmids might be involved in the chromosome-based regulatory networks implicated in Y. pestis-specific physiological processes.
Insights
Small regulatory RNAs (sRNAs) like HmsA are key to Yersinia pestis biofilm formation. This study shows HmsA activates biofilm synthesis genes, impacting pathogen transmission.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Yersinia pestis biofilm formation is crucial for flea transmission.
- Acquisition of plasmids (pPCP1, pMT1) and biofilm ability occurred during evolution from Yersinia pseudotuberculosis.
- Small regulatory RNAs (sRNAs) are implicated in Y. pestis biofilm formation and pathogenesis.
Purpose of the Study:
- To investigate the role of the pPCP1-derived sRNA HmsA in Yersinia pestis biofilm formation.
- To elucidate the regulatory mechanisms of HmsA on biofilm synthesis and degradation genes.
- To understand HmsA's impact on other biofilm regulators like HmsB, RovM, and RovA.
Main Methods:
- Deletion mutant construction (hmsA deletion).
- Quantification of cyclic diguanylate monophosphate (c-di-GMP) levels.
- Analysis of mRNA transcript abundance for biofilm-associated genes using primer extension, RT-PCR, and lacZ transcriptional fusion assays.
- Assessment of regulatory effects on hmsP, HmsB, rovM, and rovA.
Main Results:
- Deletion of hmsA significantly reduced c-di-GMP concentration.
- HmsA positively regulated biofilm synthesis genes (hmsHFRS, hmsT, hmsCDE) but not the degradation gene hmsP.
- HmsA deletion led to rapid degradation of the sRNA HmsB and affected regulation of rovM and rovA.
- HmsA's regulatory effects correlated with the observed HmsA-mediated biofilm phenotype.
Conclusions:
- HmsA acts as a potential activator of biofilm formation in Yersinia pestis.
- sRNAs encoded on laterally acquired plasmids may integrate into chromosome-based regulatory networks for Y. pestis-specific functions.
- HmsA plays a significant role in regulating Y. pestis biofilm development and potentially its transmission dynamics.
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