Biology Department, University of San Diego, San Diego, CA 92110, USA.
Arch Microbiol. 2011 Jun;193(6):451-9. doi: 10.1007/s00203-011-0676-y. Epub 2011 Jan 18.
The α-proteobacterium, Rhodospirillum centenum, has a complex life cycle that allows adaptation to different environments. Transitions between vegetative swim cell and swarmer cell types depend on whether the organism is growing in liquid surroundings or on a solid substrate. Moreover, starvation can induce vegetative cells to differentiate into quiescent cysts. This paper describes the results of our investigation into the role of a putative DNA-binding response regulator that is homologous to CtrA, the cell cycle regulator from Caulobacter crescentus. Deletion of ctrA from the R. centenum genome resulted in a viable strain with impaired swarming motility coupled with an increased tendency to form cysts. Conversely, overexpression of wild type CtrA or a phosphomimetic allele, CtrAD51E, suppressed cyst cell formation, whereas overexpression of a CtrAD51A allele failed to suppress encystment but did prevent swarming motility. Thus, we propose that CtrA participates within a two-component signal transduction pathway that promotes swarming motility while contributing to the suppression of cyst cell formation.
α-变形菌 Rhodospirillum centenum 具有复杂的生命周期，使其能够适应不同的环境。营养细胞和游动细胞之间的转换取决于生物体是在液体环境中生长还是在固体基质上生长。此外，饥饿可以诱导营养细胞分化为休眠的胞囊。本文描述了我们对假定的 DNA 结合反应调节因子的研究结果，该因子与 Caulobacter crescentus 的细胞周期调节因子 CtrA 同源。从 R. centenum 基因组中缺失 ctrA 会导致产生一种可行的菌株，该菌株的游动运动能力受损，同时形成胞囊的趋势增加。相反，过表达野生型 CtrA 或磷酸模拟等位基因 CtrAD51E 会抑制胞囊形成，而过表达 CtrAD51A 等位基因不能抑制胞囊形成，但可以阻止游动运动。因此，我们提出 CtrA 参与了一个双组分信号转导途径，该途径促进游动运动，同时有助于抑制胞囊形成。
