Shiomi Daisuke, Sakai Masako, Niki Hironori
Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima, Japan.
EMBO J. 2008 Dec 3;27(23):3081-91. doi: 10.1038/emboj.2008.234. Epub 2008 Nov 13.
Cell shape is critical for growth, and some genes are involved in bacterial cell morphogenesis. Here, we report a novel gene, rodZ, required for the determination of rod shape in Escherichia coli. Cells lacking rodZ no longer had rod shape but rather were round or oval. These round cells were smaller than known round mutant cells, including mreB and pbpA mutants; both are known to lose rod shape. Morphogenesis from rod cells to round cells and vice versa, caused by depletion and overproduction of RodZ, respectively, revealed that RodZ could regulate the length of the long axis of the cell. RodZ is a membrane protein with bitopic topology such that the N-terminal region including a helix-turn-helix motif is in the cytoplasm, whereas the C-terminal region is exposed in the periplasm. GFP-RodZ forms spirals along the lateral axis of the cell beneath the cell membrane, similar to the MreB bacterial actin. Thus, RodZ may mediate spatial information from cytoskeletal proteins in the cytoplasm to a peptidoglycan synthesis machinery in the periplasm.
细胞形态对于生长至关重要，一些基因参与细菌细胞形态发生。在此，我们报道了一个新基因rodZ，它是大肠杆菌杆状形态确定所必需的。缺乏rodZ的细胞不再具有杆状形态，而是呈圆形或椭圆形。这些圆形细胞比已知的圆形突变体细胞小，包括mreB和pbpA突变体；已知这两种突变体都会失去杆状形态。分别由RodZ的耗尽和过量产生导致的从杆状细胞到圆形细胞以及反之的形态发生，表明RodZ可以调节细胞长轴的长度。RodZ是一种具有双拓扑结构的膜蛋白，其包含螺旋-转角-螺旋基序的N端区域位于细胞质中，而C端区域暴露于周质中。GFP-RodZ沿着细胞膜下方细胞的侧轴形成螺旋，类似于MreB细菌肌动蛋白。因此，RodZ可能将细胞质中细胞骨架蛋白的空间信息传递给周质中的肽聚糖合成机制。
