Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany.
Department of Biology, Philipps-Universität Marburg, Marburg, Germany.
Nat Commun. 2021 Jan 22;12(1):545. doi: 10.1038/s41467-020-20739-3.
In Rhizobiales bacteria, such as Sinorhizobium meliloti, cell elongation takes place only at new cell poles, generated by cell division. Here, we show that the role of the FtsN-like protein RgsS in S. meliloti extends beyond cell division. RgsS contains a conserved SPOR domain known to bind amidase-processed peptidoglycan. This part of RgsS and peptidoglycan amidase AmiC are crucial for reliable selection of the new cell pole as cell elongation zone. Absence of these components increases mobility of RgsS molecules, as well as abnormal RgsS accumulation and positioning of the growth zone at the old cell pole in about one third of the cells. These cells with inverted growth polarity are able to complete the cell cycle but show partially impaired chromosome segregation. We propose that amidase-processed peptidoglycan provides a landmark for RgsS to generate cell polarity in unipolarly growing Rhizobiales.
在根瘤菌目中的细菌中，如苜蓿中华根瘤菌（Sinorhizobium meliloti），细胞伸长仅发生在由细胞分裂产生的新细胞极处。在这里，我们表明 FtsN 样蛋白 RgsS 在苜蓿中华根瘤菌中的作用不仅限于细胞分裂。RgsS 包含一个保守的 SPOR 结构域，已知该结构域与经过酰胺酶处理的肽聚糖结合。RgsS 的这一部分和肽聚糖酰胺酶 AmiC 对于新细胞极作为细胞伸长区的可靠选择至关重要。缺少这些成分会增加 RgsS 分子的迁移性，以及异常的 RgsS 积累和生长区在旧细胞极的定位，这种情况约占细胞的三分之一。这些具有倒置生长极性的细胞能够完成细胞周期，但显示出部分染色体分离受损。我们提出，经过酰胺酶处理的肽聚糖为 RgsS 提供了一个地标，以在单极生长的根瘤菌目中产生细胞极性。
