Elucidation of localization mechanism of the cell surface proteins in bacteria

dl -内肽酶是枯草芽孢杆菌维持形状和生长所需的细胞壁水解酶。隔膜上的LytF主要在细胞分离中起作用。另一方面，除了细胞分离外，隔膜和侧壁的LytE对细胞的延伸也是必需的。在这项研究中，我们研究了阐明这些酶的定位和功能所需的关键因素。当LytF与LytE的信号肽（SPLytE）一起表达时，它不仅可以定位于鼻中隔和两极，还可以定位于侧壁。此外，SPLytE-LytF可以部分抑制lytE和cwlO双突变的合成致死表型。这些结果有力地表明，信号肽控制着细胞壁水解酶的定位和功能。进一步分析表明SPLytE疏水部分的前半区可能对LytE的功能起重要作用。

DL-endopeptidases are cell wall hydrolases required for shape maintenance and growth in Bacillus subtilis. LytF at septum mainly functions in cell separation. On the other hand, LytE at septum and along sidewall is required for cell elongation in addition to cell separation. In this study, we examined to elucidate what is a key factor required for localization and function of these enzymes. When LytF was expressed with a signal peptide of LytE (SPLytE), it has been localizable not only septum and poles but also along the sidewall. Moreover, SPLytE-LytF could partially suppress a synthetic lethal phenotype of the double mutation in lytE and cwlO. These results strongly suggest that signal peptide governs localization and function of the cell wall hydrolases. Further analyses indicated that the first half region in the hydrophobic part of SPLytE might play an important role for the function of LytE.