Faculty of Biology, Philipps-Universität, Marburg, Germany.
Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
PLoS Genet. 2019 Feb 1;15(2):e1007897. doi: 10.1371/journal.pgen.1007897. eCollection 2019 Feb.
Many bacteria have complex cell shapes, but the mechanisms producing their distinctive morphologies are still poorly understood. Caulobacter crescentus, for instance, exhibits a stalk-like extension that carries an adhesive holdfast mediating surface attachment. This structure forms through zonal peptidoglycan biosynthesis at the old cell pole and elongates extensively under phosphate-limiting conditions. We analyzed the composition of cell body and stalk peptidoglycan and identified significant differences in the nature and proportion of peptide crosslinks, indicating that the stalk represents a distinct subcellular domain with specific mechanical properties. To identify factors that participate in stalk formation, we systematically inactivated and localized predicted components of the cell wall biosynthetic machinery of C. crescentus. Our results show that the biosynthesis of stalk peptidoglycan involves a dedicated peptidoglycan biosynthetic complex that combines specific components of the divisome and elongasome, suggesting that the repurposing of preexisting machinery provides a straightforward means to evolve new morphological traits.
许多细菌具有复杂的细胞形状，但产生这些独特形态的机制仍知之甚少。例如，新月柄杆菌呈现出一种类似于柄的延伸结构，携带一个粘性固着器，介导表面附着。这个结构通过在旧细胞极的区域化肽聚糖生物合成形成，并在磷酸盐限制条件下广泛伸长。我们分析了细胞体和柄的肽聚糖组成，发现肽交联的性质和比例有显著差异，表明柄代表一个具有特定机械性质的独特的细胞内区域。为了鉴定参与柄形成的因素，我们系统地失活和定位了新月柄杆菌细胞壁生物合成机制的预测成分。我们的结果表明，柄肽聚糖的生物合成涉及一个专门的肽聚糖生物合成复合物，该复合物结合了分裂体和伸长体的特定成分，这表明对现有机制的重新利用为进化新的形态特征提供了一种直接的手段。
