CovR and VicRK regulate cell surface biogenesis genes required for biofilm formation in Streptococcus mutans.
CovR and VicRK regulate cell surface biogenesis genes required for biofilm formation in Streptococcus mutans.
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DOI：
10.1371/journal.pone.0058271
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Mattos-Graner RO
中科院分区：
文献类型：
--
作者：
Stipp RN;Boisvert H;Smith DJ;Höfling JF;Duncan MJ;Mattos-Graner RO
变形链球菌的双组分系统VicRK和孤儿调节因子COVR共同调节一组毒力基因，这些基因与生物膜基质的胞外多糖的合成和相互作用有关。Vick和COVR基因敲除突变体表现出异常的细胞分裂和形态表型，尽管所涉及的基因功能缺陷尚不清楚。通过将亲本菌株UA159与Vick(UAvic)或Covr(UAcov)缺失突变体进行转录转录比较，并结合凝胶动力改变分析(EMSA)，我们鉴定了在细胞壁/表面生物发生中直接受VICR和COVR调控的基因，包括gbpB、wapE、SMA、SMU、2146c和lysM。由VICR和COVR(wapE，lysM，SMAA)或仅由VICR(SMU 2146c)或COVR(EPSC)调控的基因的缺失突变可促进生物膜起始的显著变化，包括增加脆性，微集落形成缺陷，以及不典型的细胞形态和/或连锁。在SmaA、wapE、lysM、SMU 2146c和EPSC的敲除突变体中，观察到在生长过程中毛脲溶解活性显著降低和/或DNA释放增加，这意味着在细胞壁生物发生中发挥了作用。WapE和lysM突变也影响细胞的疏水性和对渗透或氧化应激的敏感性。最后，在生物膜启动过程中，VICR、COVR和VicRK/COVR-靶(gbpB、wapE、SMAA、SMU 2146c、lysM、EPSC)在UA159中上调，这是一种蔗糖依赖的方式。这些数据支持一个模型，在该模型中，VicRK和COVR协调细胞分裂和表面生物发生与胞外多糖的合成，这一过程显然是在蔗糖存在下形成结构稳定的生物膜所必需的。
The two-component system VicRK and the orphan regulator CovR of Streptococcus mutans co-regulate a group of virulence genes associated with the synthesis of and interaction with extracellular polysaccharides of the biofilm matrix. Knockout mutants of vicK and covR display abnormal cell division and morphology phenotypes, although the gene function defects involved are as yet unknown. Using transcriptomic comparisons between parent strain UA159 with vicK (UAvic) or covR (UAcov) deletion mutants together with electrophoretic motility shift assays (EMSA), we identified genes directly regulated by both VicR and CovR with putative functions in cell wall/surface biogenesis, including gbpB, wapE, smaA, SMU.2146c, and lysM. Deletion mutants of genes regulated by VicR and CovR (wapE, lysM, smaA), or regulated only by VicR (SMU.2146c) or CovR (epsC) promoted significant alterations in biofilm initiation, including increased fragility, defects in microcolony formation, and atypical cell morphology and/or chaining. Significant reductions in mureinolytic activity and/or increases in DNA release during growth were observed in knockout mutants of smaA, wapE, lysM, SMU.2146c and epsC, implying roles in cell wall biogenesis. WapE and lysM mutations also affected cell hydrophobicity and sensitivity to osmotic or oxidative stress. Finally, vicR, covR and VicRK/CovR-targets (gbpB, wapE, smaA, SMU.2146c, lysM, epsC) are up-regulated in UA159 during biofilm initiation, in a sucrose-dependent manner. These data support a model in which VicRK and CovR coordinate cell division and surface biogenesis with the extracellular synthesis of polysaccharides, a process apparently required for formation of structurally stable biofilms in the presence of sucrose.
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