Morphogenesis and Microbial Growth Lab, Institut Pasteur, Paris, France.
Université de Paris, Paris, France.
EMBO J. 2023 Jul 17;42(14):e112168. doi: 10.15252/embj.2022112168. Epub 2023 Jun 1.
All bacterial cells must expand their envelopes during growth. The main load-bearing and shape-determining component of the bacterial envelope is the peptidoglycan cell wall. Bacterial envelope growth and shape changes are often thought to be controlled through enzymatic cell wall insertion. We investigated the role of cell wall insertion for cell shape changes during cell elongation in Gram-negative bacteria. We found that both global and local rates of envelope growth of Escherichia coli remain nearly unperturbed upon arrest of cell wall insertion-up to the point of sudden cell lysis. Specifically, cells continue to expand their surface areas in proportion to biomass growth rate, even if the rate of mass growth changes. Other Gram-negative bacteria behave similarly. Furthermore, cells plastically change cell shape in response to differential mechanical forces. Overall, we conclude that cell wall-cleaving enzymes can control envelope growth independently of synthesis. Accordingly, the strong overexpression of an endopeptidase leads to transiently accelerated bacterial cell elongation. Our study demonstrates that biomass growth and envelope forces can guide cell envelope expansion through mechanisms that are independent of cell wall insertion.
所有细菌细胞在生长过程中都必须扩大其包膜。细菌包膜的主要承重和形状确定成分是肽聚糖细胞壁。包膜生长和形状变化通常被认为是通过酶促细胞壁插入来控制的。我们研究了细胞壁插入在革兰氏阴性菌细胞伸长过程中细胞形状变化中的作用。我们发现，即使在质量生长速率发生变化的情况下，大肠杆菌的包膜生长的全局和局部速率在细胞壁插入停止时仍几乎未受干扰，直至突然发生细胞裂解。具体来说，细胞继续按生物量生长速率的比例扩大其表面积。其他革兰氏阴性菌也表现出类似的行为。此外，细胞可以响应不同的机械力而塑性改变细胞形状。总的来说，我们得出结论，细胞壁裂解酶可以独立于合成来控制包膜生长。因此，内切酶的过强表达会导致细菌细胞的短暂伸长加速。我们的研究表明，生物量生长和包膜力可以通过独立于细胞壁插入的机制来指导细胞包膜的扩展。
