Downregulation of GbpB, a Component of the VicRK Regulon, Affects Biofilm Formation and Cell Surface Characteristics of Streptococcus mutans
Downregulation of GbpB, a Component of the VicRK Regulon, Affects Biofilm Formation and Cell Surface Characteristics of Streptococcus mutans
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DOI：
10.1128/iai.00725-10
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发表时间：
2011-02-01
影响因子：
3.1
通讯作者：
Mattos-Graner, Renata O.
中科院分区：
文献类型：
--
作者：
Duque, Cristiane;Stipp, Rafael N.;Mattos-Graner, Renata O.
龋齿病原体变形链球菌的毒力部分依赖于葡聚糖的蔗糖依赖性合成和与葡聚糖的相互作用，葡聚糖是牙齿生物膜的细胞外基质的主要组分。然而，S.变异体参与生物膜生长仍有待阐明。在这项研究中，我们进一步研究GbpB，一个重要的免疫显性蛋白质与相似的胞壁蛋白水解酶。在菌株UA159（UACA2）中构建了在四环素诱导型启动子控制下表达gbpB反义RNA的条件性敲低突变体，并用于研究GbpB耗尽对生物膜形成和细胞表面相关特征的影响。此外，研究了由双组分系统VicRK对gbpB的调节，并进行了vicK突变体（UAvicK）的表型分析。GbpB直接受VicR调控，UACA 2和UAvicK之间的几个表型变化是可比的，尽管这些菌株之间存在差异。已确定GbpB耗竭损害蔗糖依赖性生物膜形成的初始阶段，而外源性天然GbpB部分恢复生物膜表型。几个细胞性状显着影响GbpB耗竭，包括改变细胞形状，减少自溶，增加细胞疏水性，抗生素和渗透和氧化应激的敏感性。这些数据为GbpB参与蔗糖依赖性生物膜形成和细胞表面性质提供了第一个实验证据。
The virulence of the dental caries pathogen Streptococcus mutans relies in part on the sucrose-dependent synthesis of and interaction with glucan, a major component of the extracellular matrix of tooth biofilms. However, the mechanisms by which secreted and/or cell-associated glucan-binding proteins (Gbps) produced by S. mutans participate in biofilm growth remain to be elucidated. In this study, we further investigate GbpB, an essential immunodominant protein with similarity to murein hydrolases. A conditional knockdown mutant that expressed gbpB antisense RNA under the control of a tetracycline-inducible promoter was constructed in strain UA159 (UACA2) and used to investigate the effects of GbpB depletion on biofilm formation and cell surface-associated characteristics. Additionally, regulation of gbpB by the two-component system VicRK was investigated, and phenotypic analysis of a vicK mutant (UAvicK) was performed. GbpB was directly regulated by VicR, and several phenotypic changes were comparable between UACA2 and UAvicK, although differences between these strains existed. It was established that GbpB depletion impaired initial phases of sucrose-dependent biofilm formation, while exogenous native GbpB partially restored the biofilm phenotype. Several cellular traits were significantly affected by GbpB depletion, including altered cell shape, decreased autolysis, increased cell hydrophobicity, and sensitivity to antibiotics and osmotic and oxidative stresses. These data provide the first experimental evidence for GbpB participation in sucrose-dependent biofilm formation and in cell surface properties.