Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Seville, Seville, Spain.
mBio. 2022 Aug 30;13(4):e0116522. doi: 10.1128/mbio.01165-22. Epub 2022 Jul 25.
Bacteria in general serve two main tasks: cell growth and division. Both processes include peptidoglycan extension to allow cell expansion and to form the poles of the daughter cells, respectively. The cyanobacterium forms filaments of communicated cells in which the outer membrane and the peptidoglycan sacculus, which is engrossed in the intercellular regions between contiguous cells, are continuous along the filament. During the growth of , peptidoglycan incorporation was weak at the cell periphery. During cell division, midcell peptidoglycan incorporation matched the localization of the divisome, and incorporation persisted in the intercellular septa, even after the division was completed. MreB, MreC, and MreD were located throughout the cell periphery and, in contrast to other bacteria, also to the divisome all along midcell peptidoglycan growth. In mutants bearing inactivated , or genes, which showed conspicuous alterations in the filament morphology, consecutive septal bands of peptidoglycan growth were frequently not parallel to each other and were irregularly spaced along the filament, reproducing the disposition of the Z-ring. Both lateral and septal growth was impaired in strains down-expressing Z-ring components, and MreB and MreD appeared to directly interact with some divisome components. We propose that, in , association with the divisome is a way for localization of MreB, MreC, and MreD at the cell poles, where they regulate lateral, midcell, and septal peptidoglycan growth with the latter being involved in localization and maintenance of the intercellular septal-junction protein structures that mediate cell-cell communication along the filament. Peptidoglycan surrounds the bacterial cell, being essential for the determination of the bacterium-specific morphology and survival. Peptidoglycan growth has been thoroughly investigated in some model rod-shaped bacteria, and more recently some representatives with disparate morphologies became into focus, revealing that patterns of peptidoglycan growth are much more diverse than previously anticipated. forms filaments of communicated cells exhibiting features of multicellular organisms, such as the production of morphogens and coupled circadian oscillations. Here, we showed that presented a distinct pattern of peptidoglycan growth characterized by continuous incorporation of material at the polar intercellular regions, contributing to assembling and maintaining the protein complexes that expand the septal peptidoglycan mediating intercellular molecular exchange in the filament.
细胞生长和分裂。这两个过程都包括肽聚糖的延伸，以允许细胞扩张，并分别形成子细胞的极。蓝细菌形成沟通细胞的丝状结构，其中外膜和被卷入相邻细胞之间的细胞间区域的肽聚糖囊泡在丝状体中是连续的。在 的生长过程中，细胞壁的肽聚糖掺入在细胞边缘较弱。在细胞分裂过程中，中隔处的肽聚糖掺入与分裂体的定位相匹配，并且掺入在细胞间隔中持续存在，即使在分裂完成后也是如此。MreB、MreC 和 MreD 位于整个细胞边缘，与其他细菌不同，它们也沿着中隔处的肽聚糖生长一直位于分裂体。在缺失 或 基因失活的 突变体中，丝状形态发生明显改变，连续的肽聚糖生长隔带经常彼此不平行，并且沿着丝状体不规则地间隔，重现了 Z 环的排布。在 Z 环成分表达下调的菌株中，侧向和隔带生长都受到了损害，并且 MreB 和 MreD 似乎与一些分裂体成分直接相互作用。我们提出，在 中，与分裂体的关联是将 MreB、MreC 和 MreD 定位在细胞极的一种方式，在那里它们调节侧向、中隔和隔带的肽聚糖生长，而后者参与了细胞间隔蛋白结构的定位和维持，这些结构介导了丝状结构中沿丝状体的细胞间通讯。肽聚糖环绕着细菌细胞，对于确定细菌特有的形态和生存至关重要。在一些模式杆状细菌中，肽聚糖的生长已经得到了深入研究，而最近一些形态不同的代表成为了焦点，这表明肽聚糖的生长模式比以前预期的要多样化得多。形成沟通细胞的丝状结构，表现出多细胞生物的特征，如形态发生素的产生和耦合的生物钟振荡。在这里，我们表明 呈现出独特的肽聚糖生长模式，其特征是在极性细胞间区域持续掺入物质，有助于组装和维持扩展隔段肽聚糖的蛋白质复合物，从而介导丝状结构中细胞间的分子交换。
