Role of prolipoprotein diacylglyceryl transferase (Lgt) and lipoprotein-specific signal peptidase II (LspA) in localization and physiological function of lipoprotein MsmE in Streptococcus mutans
Role of prolipoprotein diacylglyceryl transferase (Lgt) and lipoprotein-specific signal peptidase II (LspA) in localization and physiological function of lipoprotein MsmE in Streptococcus mutans
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DOI：
10.1111/j.1399-302x.2008.00455.x
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发表时间：
2008-12-01
影响因子：
--
通讯作者：
Igarashi, T.
中科院分区：
文献类型：
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作者：
Arimoto, T.;Igarashi, T.
简介：为了阐明前脂蛋白二酰基甘油转移酶（Lgt）和脂蛋白特异性信号肽酶II（LspA）在MsmE生理功能中的作用，我们构建了变形链球菌109 c的lgt缺陷型和lspA缺陷型突变体，并研究了Lgt和LspA的潜在作用。在S.方法：用lgt、lspA和msmE缺陷突变株对变形链球菌进行突变。通过它们各自的基因的双交换重组构建变异株109 c。用MsmE抗血清通过Western印迹分析证明MsmE的定位。S.结果：变形链球菌细胞在胰蛋白胨培养基中分别加入蜜二糖和葡萄糖。变形杆菌lgt突变体的表面脂蛋白MsmE的定位随着培养上清的改变而改变。S.在蜜二糖培养基中，变异株lgt和lspA突变体的生长显著减少;然而，在补充了lgt或lspA基因的菌株中，生长恢复。因此，Lgt修饰脂质和随后LspA切割信号肽对膜锚定和S.结论：这些结果表明MsmE是S. mutans中蜜二糖代谢所必需的。Lgt和LspA对MsmE的修饰是MsmE发挥生理功能的重要过程。
Introduction: To clarify the role that prolipoprotein diacylglyceryl transferase (Lgt) and lipoprotein-specific signal peptidase II (LspA) play in the physiological function of MsmE, we constructed lgt-deficient and lspA-deficient mutants of Streptococcus mutans 109c and examined the potential role of Lgt and LspA in membrane anchoring and growth in a melibiose medium of S. mutans.Methods: The lgt-, lspA-, and msmE-deficient mutants of S. mutans 109c were constructed by double-crossover recombination of their respective genes. Localization of MsmE was demonstrated by Western blot analysis with an MsmE antiserum. The growth of S. mutans cells was examined in a Trypton medium containing melibiose or glucose.Results: In the S. mutans lgt mutant, localization of the surface lipoprotein MsmE changed with the culture supernatant. The growth of the S. mutans lgt and lspA mutants was remarkably reduced in the melibiose medium; however, growth was recovered in the strains complemented with the lgt or the lspA gene. Therefore, lipid-modification by Lgt and subsequent signal peptide cleavage by LspA were crucial for membrane anchoring and the physiological function of MsmE in S. mutans.Conclusions: These results demonstrate that MsmE is required for melibiose metabolism in S. mutans and that modification by Lgt and LspA are important processes for the physiological function of MsmE.