Inactivation of the Autolysis-Related Genes lrgB and yycI in Staphylococcus aureus Increases Cell Lysis-Dependent eDNA Release and Enhances Biofilm Development In Vitro and In Vivo.
Inactivation of the Autolysis-Related Genes lrgB and yycI in Staphylococcus aureus Increases Cell Lysis-Dependent eDNA Release and Enhances Biofilm Development In Vitro and In Vivo.
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DOI：
10.1371/journal.pone.0138924
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Figueiredo AM
中科院分区：
文献类型：
--
作者：
Beltrame CO;Côrtes MF;Bonelli RR;Côrrea AB;Botelho AM;Américo MA;Fracalanzza SE;Figueiredo AM
金黄色葡萄球菌不依赖的生物膜本质上是多因子的，各种细菌蛋白与生物膜的发育有关，包括纤维连接蛋白结合蛋白A和B、蛋白A、表面蛋白SasG、蛋白酶和一些自溶蛋白。细胞外DNA （eDNA）的作用也已在一些金黄色葡萄球菌生物膜中得到证实。在此，我们构建了Tn551文库，筛选出影响生物膜形成的两个基因，lrgB和yycI。在等位基因重组构建的敲除菌株中也证实了这两个基因对生物膜发育的抑制作用。相比之下，镉诱导启动子超表达lrgB或yycI导致生物膜积累减少。事实上，当lrgB或yycI失活时，检测到细胞裂解依赖的eDNA释放显著增加，这解释了这些突变体形成的增强的生物膜。事实上，lrgB和yycI基因属于不同的操纵子，它们通过非常不同的机制抑制细菌自溶。LrgB与噬菌体保持素/抗保持素类似物的合成有关，而YycI参与双组分系统YycGF （WalKR）的激活/抑制。我们的体内数据表明，在异物动物模型中，自溶素激活导致细菌毒力增加，因为从接种了lrgB或yycI敲除突变体的植入导管中恢复了更多的附着细胞。
Staphylococcus aureus ica-independent biofilms are multifactorial in nature, and various bacterial proteins have been associated with biofilm development, including fibronectin-binding proteins A and B, protein A, surface protein SasG, proteases, and some autolysins. The role of extracellular DNA (eDNA) has also been demonstrated in some S. aureus biofilms. Here, we constructed a Tn551 library, and the screening identified two genes that affected biofilm formation, lrgB and yycI. The repressive effect of both genes on the development of biofilm was also confirmed in knockout strains constructed by allelic recombination. In contrast, the superexpression of either lrgB or yycI by a cadmium-inducible promoter led to a decrease in biofilm accumulation. Indeed, a significant increase in the cell-lysis dependent eDNA release was detected when lrgB or yycI were inactivated, explaining the enhanced biofilm formed by these mutants. In fact, lrgB and yycI genes belong to distinct operons that repress bacterial autolysis through very different mechanisms. LrgB is associated with the synthesis of phage holin/anti-holin analogues, while YycI participates in the activation/repression of the two-component system YycGF (WalKR). Our in vivo data suggest that autolysins activation lead to increased bacterial virulence in the foreign body animal model since a higher number of attached cells was recovered from the implanted catheters inoculated with lrgB or yycI knockout mutants.