Cell shape and cell-wall organization in Gram-negative bacteria
Cell shape and cell-wall organization in Gram-negative bacteria
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DOI：
10.1073/pnas.0805309105
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发表时间：
2008-12-09
影响因子：
11.1
通讯作者：
Wingreen, Ned S.
中科院分区：
文献类型：
--
作者：
Huang, Kerwyn Casey;Mukhopadhyay, Ranjan;Wingreen, Ned S.
在细菌细胞中，肽聚糖细胞壁是决定细胞形状的承压结构。尽管细胞壁成分的组成和组装的许多分子细节是已知的，但在正常生长过程中，肽多聚糖亚单位网络是如何组织成细胞形状的，以及它如何在损伤或环境压力下进行重组还没有被探索过。在这项工作中，我们引入了一个细菌细胞壁的定量物理模型，该模型预测了杆状革兰氏阴性杆菌大肠杆菌中细胞形状对肽聚糖损伤和扰动的机械响应。为了验证这些预测，我们使用延时成像实验来表明，损伤通常表现为侧壁上的凸起，加上凸起周围圆柱形细胞壁的大规模弯曲。我们的物理模型还表明，细胞形状对肽聚糖缺陷具有惊人的健壮性，这有助于解释观察到的细胞壁孔洞以及细胞即使在限制肽交联的条件下也能生长和保持其形状的能力。最后，我们证明了许多常见的细菌细胞形状可以通过肽聚糖缺陷的简单空间图案在同一模型中实现，这表明微小的图案变化可能是在细菌王国中观察到的巨大形状多样性的基础。
In bacterial cells, the peptidoglycan cell wall is the stress-bearing structure that dictates cell shape. Although many molecular details of the composition and assembly of cell-wall components are known, how the network of peptidoglycan subunits is organized to give the cell shape during normal growth and how it is reorganized in response to damage or environmental forces have been relatively unexplored. In this work, we introduce a quantitative physical model of the bacterial cell wall that predicts the mechanical response of cell shape to peptidoglycan damage and perturbation in the rod-shaped Gram-negative bacterium Escherichia coli. To test these predictions, we use time-lapse imaging experiments to show that damage often manifests as a bulge on the sidewall, coupled to large-scale bending of the cylindrical cell wall around the bulge. Our physical model also suggests a surprising robustness of cell shape to peptidoglycan defects, helping explain the observed porosity of the cell wall and the ability of cells to grow and maintain their shape even under conditions that limit peptide crosslinking. Finally, we show that many common bacterial cell shapes can be realized within the same model via simple spatial patterning of peptidoglycan defects, suggesting that minor patterning changes could underlie the great diversity of shapes observed in the bacterial kingdom.