Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
J Bacteriol. 2010 Oct;192(19):4847-58. doi: 10.1128/JB.00607-10. Epub 2010 Aug 6.
Cell division in Caulobacter crescentus involves constriction and fission of the inner membrane (IM) followed about 20 min later by fission of the outer membrane (OM) and daughter cell separation. In contrast to Escherichia coli, the Caulobacter Tol-Pal complex is essential. Cryo-electron microscopy images of the Caulobacter cell envelope exhibited outer membrane disruption, and cells failed to complete cell division in TolA, TolB, or Pal mutant strains. In wild-type cells, components of the Tol-Pal complex localize to the division plane in early predivisional cells and remain predominantly at the new pole of swarmer and stalked progeny upon completion of division. The Tol-Pal complex is required to maintain the position of the transmembrane TipN polar marker, and indirectly the PleC histidine kinase, at the cell pole, but it is not required for the polar maintenance of other transmembrane and membrane-associated polar proteins tested. Coimmunoprecipitation experiments show that both TolA and Pal interact directly or indirectly with TipN. We propose that disruption of the trans-envelope Tol-Pal complex releases TipN from its subcellular position. The Caulobacter Tol-Pal complex is thus a key component of cell envelope structure and function, mediating OM constriction at the final step of cell division as well as the positioning of a protein localization factor.
在新月柄杆菌中，细胞分裂涉及内膜（IM）的收缩和分裂，大约 20 分钟后，外膜（OM）和子细胞分离。与大肠杆菌不同的是，新月柄杆菌 Tol-Pal 复合物是必需的。用冷冻电子显微镜观察新月柄杆菌细胞包膜的图像显示，外膜被破坏，在 TolA、TolB 或 Pal 突变株中，细胞无法完成细胞分裂。在野生型细胞中，Tol-Pal 复合物的成分定位于早期预分裂细胞的分裂平面上，并且在完成分裂后，主要位于游动细胞和 stalked 后代的新极点。Tol-Pal 复合物对于维持跨膜 TipN 极性标记物的位置是必需的，并且间接对于 PleC 组氨酸激酶在细胞极点的位置也是必需的，但对于其他跨膜和膜相关的极性蛋白的极性维持不是必需的。共免疫沉淀实验表明，TolA 和 Pal 都直接或间接地与 TipN 相互作用。我们提出，跨膜 Tol-Pal 复合物的破坏将 TipN 从其亚细胞位置释放出来。因此，新月柄杆菌 Tol-Pal 复合物是细胞包膜结构和功能的关键组成部分，在细胞分裂的最后一步介导 OM 的收缩，以及定位蛋白定位因子。
