Bacillus subtilis cell diameter is determined by the opposing actions of two distinct cell wall synthetic systems
Bacillus subtilis cell diameter is determined by the opposing actions of two distinct cell wall synthetic systems
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DOI：
10.1038/s41564-019-0439-0
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发表时间：
2019-08-01
影响因子：
28.3
通讯作者：
Garner, Ethan C.
中科院分区：
文献类型：
--
作者：
Dion, Michael F.;Kapoor, Mrinal;Garner, Ethan C.
杆状细菌通过两种空间上不同的酶系统的作用将材料添加到它们的细胞壁中而生长：杆状复合物围绕细胞圆周移动，而A类青霉素结合蛋白（aPBPs）则不。为了了解这两个系统的联合作用如何定义细菌的尺寸，我们研究了每个系统如何影响枯草芽孢杆菌的生长和宽度，以及它们的球囊内材料的机械各向异性和方向。杆的宽度不是由MreB决定的，而是取决于系统之间的平衡：杆复合物减少直径，而aPBPs增加它。杆复合物活性的增加与定向MreB丝密度的增加和定向PBP2a酶的更大比例相关。这种增加的周向合成增加了球囊内定向材料的相对量，使它们更能抵抗横跨其宽度的拉伸，从而增强了杆状。总之，这些实验解释了两个主要细胞壁合成系统的联合作用如何构建和维持不同宽度的杆。大肠杆菌杆状突变体也显示出宽度和方向性MreB细丝密度之间的相同相关性，表明该模型可以推广到通过杆状复合体伸长的细菌。
Rod-shaped bacteria grow by adding material into their cell wall via the action of two spatially distinct enzymatic systems: the Rod complex moves around the cell circumference, whereas class A penicillin-binding proteins (aPBPs) do not. To understand how the combined action of these two systems defines bacterial dimensions, we examined how each affects the growth and width of Bacillus subtilis as well as the mechanical anisotropy and orientation of material within their sacculi. Rod width is not determined by MreB, rather it depends on the balance between the systems: the Rod complex reduces diameter, whereas aPBPs increase it. Increased Rod-complex activity correlates with an increased density of directional MreB filaments and a greater fraction of directional PBP2a enzymes. This increased circumferential synthesis increases the relative quantity of oriented material within the sacculi, making them more resistant to stretching across their width, thereby reinforcing rod shape. Together, these experiments explain how the combined action of the two main cell wall synthetic systems builds and maintains rods of different widths. Escherichia coli Rod mutants also show the same correlation between width and directional MreB filament density, suggesting this model may be generalizable to bacteria that elongate via the Rod complex.