Liu Zizhong, Gao Xiaofang, Wang Hongduo, Fang Haihong, Yan Yanfeng, Liu Lei, Chen Rong, Zhou Dongsheng, Yang Ruifu, Han Yanping
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No. 20, Dongdajie, Fengtai, Beijing, 100071, China.
State Key Lab of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.
BMC Microbiol. 2016 Aug 4;16(1):176. doi: 10.1186/s12866-016-0793-5.
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.
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.
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.
鼠疫耶尔森菌形成生物膜的能力是该病原体在跳蚤传播中的一个重要特征。鼠疫耶尔森菌从假结核耶尔森菌进化而来时，横向获得了两个质粒（pPCP1和pMT1）以及形成生物膜的能力。小调节RNA（sRNA）被认为在生物膜形成和致病过程中起关键作用。
发现一种源自pPCP1的sRNA HmsA（也称为sR084）有助于增强鼠疫耶尔森菌的生物膜形成表型。鼠疫耶尔森菌中hmsA基因缺失后，环二鸟苷酸的浓度显著降低。通过引物延伸、RT-PCR和lacZ转录融合试验，在野生型和hmsA突变株中测量了决定胞外多糖产生的mRNA转录本丰度，胞外多糖产生对生物膜形成至关重要。HmsA正向调节生物膜合成相关基因（hmsHFRS、hmsT和hmsCDE），但对生物膜降解相关基因hmsP没有调节作用。有趣的是，最近鉴定出的生物膜激活剂sRNA HmsB在hmsA缺失突变体中迅速降解。还发现两个作为生物膜调节因子的基因（rovM和rovA）也受HmsA调节，其调节作用与HmsA介导的生物膜表型一致。
HmsA可能作为鼠疫耶尔森菌生物膜形成的激活剂，这意味着横向获得的质粒上编码的sRNA可能参与了与鼠疫耶尔森菌特异性生理过程相关的基于染色体的调控网络。
