Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
J Bacteriol. 2011 Sep;193(18):4821-31. doi: 10.1128/JB.00223-11. Epub 2011 Jul 8.
During biofilm formation by Bacillus subtilis, two extracellular matrix components are synthesized, namely, the TasA amyloid fibers and an exopolysaccharide. In addition, a small protein called YuaB has been shown to allow the biofilm to form. The regulatory protein DegU is known to initiate biofilm formation. In this report we show that the main role of DegU during biofilm formation is to indirectly drive the activation of transcription from the yuaB promoter. The N terminus of YuaB constitutes a signal peptide for the Sec transport system. Here we show that the presence of the signal peptide is required for YuaB function. In addition we demonstrate that upon export of YuaB from the cytoplasm, it localizes to the cell wall. We continue with evidence that increased production of TasA and the exopolysaccharide is not sufficient to overcome the effects of a mutation in yuaB, demonstrating the unique involvement of YuaB in forming a biofilm. In line with this, YuaB is not involved in correct synthesis, export, or polymerization of either the TasA amyloid fibers or the exopolysaccharide. Taken together, these findings identify YuaB as a protein that plays a novel role during biofilm formation. We hypothesize that YuaB functions synergistically with the known components of the biofilm matrix to facilitate the assembly of the biofilm matrix.
在枯草芽孢杆菌生物膜形成过程中，合成了两种细胞外基质成分，即 TasA 淀粉样纤维和胞外多糖。此外，一种名为 YuaB 的小蛋白已被证明可使生物膜形成。调节蛋白 DegU 已知可启动生物膜形成。在本报告中，我们表明 DegU 在生物膜形成过程中的主要作用是间接驱动 yuaB 启动子的转录激活。YuaB 的 N 端构成了 Sec 转运系统的信号肽。在这里，我们表明信号肽的存在是 YuaB 功能所必需的。此外，我们证明了 YuaB 在从细胞质输出后，会定位于细胞壁。我们继续证明 TasA 和胞外多糖产量的增加不足以克服 yuaB 突变的影响，这表明 YuaB 独特地参与了生物膜的形成。与此一致的是，YuaB 不参与 TasA 淀粉样纤维或胞外多糖的正确合成、输出或聚合。综上所述，这些发现确定了 YuaB 是一种在生物膜形成过程中发挥新作用的蛋白质。我们假设 YuaB 与生物膜基质的已知成分协同作用，促进生物膜基质的组装。
