Deficiency of MecA in Streptococcus mutans Causes Major Defects in Cell Envelope Biogenesis, Cell Division, and Biofilm Formation.
Deficiency of MecA in Streptococcus mutans Causes Major Defects in Cell Envelope Biogenesis, Cell Division, and Biofilm Formation.
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DOI：
10.3389/fmicb.2018.02130
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发表时间：
2018
影响因子：
5.2
通讯作者：
Wen ZT
中科院分区：
文献类型：
--
作者：
De A;Jorgensen AN;Beatty WL;Lemos J;Wen ZT
MecA是一种接头蛋白，指导ClpC/ p介导的蛋白水解。采用双交叉等位基因交换法构建了突变体S. mutans的meca缺陷突变体，分析了meca缺陷对细胞生物学和生物膜形成的影响。与野生型UA159不同，mecA突变体TW416形成粘液状和光滑的菌落，在肉汤中严重结块，生长速度降低。透射电镜分析显示，TW416主要生长在具有多个不对称间隔的巨大“肿胀”细胞链中，与UA159的球粒形式不同。与UA159相比，无论碳水化合物来源如何，TW416都显著减少了生物膜的形成（P < 0.001）。对TW416全细胞裂解物进行Western blot分析发现，葡萄糖转移酶GtfC和GtfB以及P1和WapA粘附素的表达减少，这可以解释TW416生物膜形成缺陷的原因。当用比色法分析时，突变鼠囊的细胞壁磷酸盐几乎比亲本菌株低20倍（P < 0.001）。然而，有趣的是，当使用UA159全细胞抗血清作为探针对小鼠囊泡制备物进行免疫印迹分析时，发现与野生型相比，TW416具有显著更高的信号强度。也有证据表明，变形链球菌中的MecA不仅仅是一种接头蛋白，尽管它如何调节细菌的病理生理，包括细胞包膜生物发生、细胞分裂和生物膜形成有待进一步研究。
MecA is an adaptor protein that guides the ClpC/P-mediated proteolysis. A S. mutans MecA-deficient mutant was constructed by double-crossover allelic exchange and analyzed for the effects of such a deficiency on cell biology and biofilm formation. Unlike the wild-type, UA159, the mecA mutant, TW416, formed mucoid and smooth colonies, severely clumped in broth and had a reduced growth rate. Transmission electron microscopy analysis revealed that TW416 grows primarily in chains of giant “swollen” cells with multiple asymmetric septa, unlike the coccoid form of UA159. As compared to UA159, biofilm formation by TW416 was significantly reduced regardless of the carbohydrate sources used for growth (P < 0.001). Western blot analysis of TW416 whole cell lysates showed a reduced expression of the glucosyltransferase GtfC and GtfB, as well as the P1 and WapA adhesins providing an explanation for the defective biofilm formation of TW416. When analyzed by a colorimetric assay, the cell wall phosphate of the mutant murein sacculi was almost 20-fold lower than the parent strain (P < 0.001). Interestingly, however, when analyzed using immunoblotting of the murein sacculi preps with UA159 whole cell antiserum as a probe, TW416 was shown to possess significantly higher signal intensity as compared to the wild-type. There is also evidence that MecA in S. mutans is more than an adaptor protein, although how it modulates the bacterial pathophysiology, including cell envelope biogenesis, cell division, and biofilm formation awaits further investigation.
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