Matsuoka Satoshi
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University.
Genes Genet Syst. 2018 Apr 10;92(5):217-221. doi: 10.1266/ggs.17-00017. Epub 2017 Oct 6.
Glyceroglycolipids are very important in Gram-positive bacteria and cyanobacteria. In Bacillus subtilis, a model organism for the Gram-positive bacteria, the ugtP mutant, which lacks glyceroglucolipids, shows abnormal morphology. Lack of glucolipids has many consequences: abnormal localization of the cytoskeletal protein MreB and activation of some extracytoplasmic function (ECF) sigma factors (σ, σ and σ) in the log phase are two examples. Conversely, the expression of monoglucosyldiacylglycerol (MGlcDG) by 1,2-diacylglycerol 3-glucosyltransferase from Acholeplasma laidlawii (alMGS) almost completely suppresses the ugtP disruptant phenotype. Activation of ECF sigmas in the ugtP mutant is decreased by alMGS expression, and is suppressed to low levels by MgSO addition. When alMGS and alDGS (A. laidlawii 1,2-diacylglycerol-3-glucose (1-2)-glucosyltransferase producing diglucosyldiacylglycerol (DGlcDG)) are simultaneously expressed, σ activation is repressed to wild type level. These observations suggest that MGlcDG molecules are required for maintenance of B. subtilis cell shape and regulation of ECF sigmas, and that DGlcDG regulates σ activity. The activation of ECF sigmas is not accompanied by proteolysis of anti-σ. Thus, glyceroglucolipids may have the specific role of helping membrane proteins function by acting in the manner of chaperones.
甘油糖脂在革兰氏阳性菌和蓝细菌中非常重要。在革兰氏阳性菌的模式生物枯草芽孢杆菌中，缺乏甘油糖脂的ugtP突变体表现出异常形态。缺乏糖脂会产生许多后果：细胞骨架蛋白MreB的定位异常以及对数期一些胞外功能（ECF）σ因子（σ、σ和σ）的激活就是两个例子。相反，来自莱氏无胆甾原体的1,2 -二酰基甘油3 -葡糖基转移酶（alMGS）表达单葡糖基二酰基甘油（MGlcDG）几乎完全抑制了ugtP破坏株的表型。alMGS的表达降低了ugtP突变体中ECF σ因子的激活，并且通过添加MgSO将其抑制到低水平。当同时表达alMGS和alDGS（产生双葡糖基二酰基甘油（DGlcDG）的莱氏无胆甾原体1,2 -二酰基甘油 - 3 -葡萄糖（1 - 2）-葡糖基转移酶）时，σ因子的激活被抑制到野生型水平。这些观察结果表明，MGlcDG分子是维持枯草芽孢杆菌细胞形态和调节ECF σ因子所必需的，并且DGlcDG调节σ因子的活性。ECF σ因子的激活并不伴随着抗σ因子的蛋白水解。因此，甘油糖脂可能具有通过以伴侣蛋白的方式发挥作用来帮助膜蛋白发挥功能的特定作用。
