Identification of an Efflux Transporter LmrB Regulating Stress Response and Extracellular Polysaccharide Synthesis in Streptococcus mutans.
Identification of an Efflux Transporter LmrB Regulating Stress Response and Extracellular Polysaccharide Synthesis in Streptococcus mutans.
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外排转运蛋白 LmrB 调节变形链球菌应激反应和胞外多糖合成的鉴定
DOI：
10.3389/fmicb.2017.00962
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发表时间：
2017
影响因子：
5.2
通讯作者：
Wei X
中科院分区：
文献类型：
--
作者：
Liu J;Guo L;Liu J;Zhang J;Zeng H;Ning Y;Wei X
外排转运蛋白参与调节细菌的毒力特性，如对抗生素的抗性、生物膜形成和定殖。变形链球菌是人类龋病的主要致病菌，其致病性依赖于其在牙齿表面形成生物膜的能力。然而，关于S.变异株的数量较少，其转运蛋白的功能尚不清楚。在这项研究中，我们确定了一个外排转运蛋白（LmrB）在S。通过将lmrB基因克隆到大肠杆菌中，将lmrB导入E.大肠杆菌具有多药耐药表型，并导致更高的EtBr外排活性，可被外排抑制剂抑制。探讨LmrB是否参与了S.为了研究变形杆菌毒力特性的调控机制，我们构建了lmrB失活突变体，并对突变体的表型进行了检测。发现LmrB缺乏导致IPS储存增加和产酸延长。在lmrB突变体中也观察到以增加的胞外多糖（EPS）产生和升高的对过氧化氢和抗微生物剂的抗性为特征的增强的生物膜形成。为了更好地理解LmrB的全局作用，使用lmrB突变株进行转录组分析。与野生型相比，lmrB突变体中有107个基因的表达上调或下调。值得注意的是，在几个基因组岛的基因表达差异调制，如应力相关的GroELS和scnRK，糖代谢相关的glg操纵子和msmREFGK转运蛋白。这些结果表明，LmrB在调控沙门氏菌几个重要的毒力特性中起着至关重要的全局作用。变种人
Efflux transporters have been implicated in regulating bacterial virulence properties such as resistance to antibiotics, biofilm formation and colonization. The pathogenicity of Streptococcus mutans, the primary etiologic agent of human dental caries, relies on the bacterium’s ability to form biofilms on tooth surface. However, the studies on efflux transporters in S. mutans are scare and the function of these transporters remained to be clarified. In this study, we identified an efflux transporter (LmrB) in S. mutans through cloning the lmrB gene into Escherichia coli. Introducing lmrB into E. coli conferred a multidrug-resistant phenotype and resulted in higher EtBr efflux activity which could be suppressed by efflux inhibitor. To explore whether LmrB was involved in S. mutans virulence properties regulation, we constructed the lmrB inactivation mutant and examined the phenotypes of the mutant. It was found that LmrB deficiency resulted in increased IPS storage and prolonged acid production. Enhanced biofilm formation characterized by increased extracellular polysaccharides (EPS) production and elevated resistance to hydrogen peroxide and antimicrobials were also observed in lmrB mutant. To gain a better understanding of the global role of LmrB, a transcriptome analysis was performed using lmrB mutant strain. The expression of 107 genes was up- or down-regulated in the lmrB mutant compared with the wild type. Notably, expression of genes in several genomic islands was differentially modulated, such as stress-related GroELS and scnRK, sugar metabolism associated glg operons and msmREFGK transporter. The results presented here indicate that LmrB plays a vital global role in the regulation of several important virulence properties in S. mutans.