Laboratoire de Chimie Bactérienne, UMR7283, Institut de Microbiologie de La Méditerranée, CNRS, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 20, France.
Institut de Microbiologie de La Méditerranée, Protein Expression Facility, CNRS, Aix Marseille Université, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 20, France.
Sci Rep. 2020 Sep 29;10(1):15938. doi: 10.1038/s41598-020-72854-2.
In bacteria, glucosamine-6-phosphate (GlcN6P) synthase, GlmS, is an enzyme required for the synthesis of Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), a precursor of peptidoglycan. In Bacillus subtilis, an UDP-GlcNAc binding protein, GlmR (formerly YvcK), essential for growth on non-glycolytic carbon sources, has been proposed to stimulate GlmS activity; this activation could be antagonized by UDP-GlcNAc. Using purified proteins, we demonstrate that GlmR directly stimulates GlmS activity and the presence of UDP-GlcNAc (at concentrations above 0.1 mM) prevents this regulation. We also showed that YvcJ, whose gene is associated with yvcK (glmR), interacts with GlmR in an UDP-GlcNAc dependent manner. Strains producing GlmR variants unable to interact with YvcJ show decreased transformation efficiency similar to that of a yvcJ null mutant. We therefore propose that, depending on the intracellular concentration of UDP-GlcNAc, GlmR interacts with either YvcJ or GlmS. When UDP-GlcNAc concentration is high, this UDP-sugar binds to YvcJ and to GlmR, blocking the stimulation of GlmS activity and driving the interaction between GlmR and YvcJ to probably regulate the cellular role of the latter. When the UDP-GlcNAc level is low, GlmR does not interact with YvcJ and thus does not regulate its cellular role but interacts with GlmS to stimulate its activity.
在细菌中，葡萄糖胺-6-磷酸（GlcN6P）合酶 GlmS 是合成尿苷二磷酸 N-乙酰葡萄糖胺（UDP-GlcNAc）所必需的酶，UDP-GlcNAc 是肽聚糖的前体。在枯草芽孢杆菌中，一种 UDP-GlcNAc 结合蛋白 GlmR（以前称为 YvcK），对于非糖酵解碳源的生长是必需的，被提议刺激 GlmS 活性；这种激活可以被 UDP-GlcNAc 拮抗。使用纯化的蛋白质，我们证明 GlmR 直接刺激 GlmS 活性，并且 UDP-GlcNAc 的存在（浓度高于 0.1mM）阻止了这种调节。我们还表明，与 yvcK（glmR）相关的基因 yvcJ 与 GlmR 以 UDP-GlcNAc 依赖的方式相互作用。产生无法与 YvcJ 相互作用的 GlmR 变体的菌株显示出与 yvcJ 缺失突变体相似的转化效率降低。因此，我们提出，根据细胞内 UDP-GlcNAc 的浓度，GlmR 要么与 YvcJ 相互作用，要么与 GlmS 相互作用。当 UDP-GlcNAc 浓度高时，这种 UDP-糖结合到 YvcJ 和 GlmR 上，阻止 GlmS 活性的刺激，并驱动 GlmR 与 YvcJ 之间的相互作用，可能调节后者的细胞作用。当 UDP-GlcNAc 水平较低时，GlmR 不会与 YvcJ 相互作用，因此不会调节其细胞作用，但会与 GlmS 相互作用以刺激其活性。
