The Sinorhizobium meliloti sensor histidine kinase CbrA contributes to free-living cell cycle regulation
The Sinorhizobium meliloti sensor histidine kinase CbrA contributes to free-living cell cycle regulation
复制标题
苜蓿中华根瘤菌传感器组氨酸激酶 CbrA 有助于自由生活的细胞周期调节
DOI：
10.1099/mic.0.067504-0
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发表时间：
2013
期刊：
影响因子：
1.5
通讯作者：
Gibson, Katherine E.
中科院分区：
文献类型：
--
作者：
Sadowski, Craig S.;Wilson, Daniel;Schallies, Karla B.;Walker, Graham;Gibson, Katherine E.
甜菜中华根瘤菌可以作为一种自由生活的细菌在土壤中定居，也可以与豆科植物寄主建立慢性细胞内感染，以达到固氮的目的。我们之前发现了这些。组氨酸激酶CbrA作为双组分传感器，在调控胞外多糖的产生、鞭毛运动和共生等方面发挥着重要作用。CbrA的系统发育分析强调了它与新月形杆菌传感器组氨酸激酶Plec和DivJ的进化关系，这两个酶通过共同的反应调节因子DivK参与CtrA依赖的细胞周期调节。因此，我们对测试CbrA是否在调节S中发挥作用产生了兴趣。Meliloticell循环过程。我们发现cbrA的丢失导致丝状细胞生长，伴随着含有异常基因组补体的细胞，表明CbrA在调节细胞分裂和可能的DNA分离方面发挥作用。S.MeliltiDivK在细胞周期的不同阶段以磷酸化依赖的方式定位在旧的细胞极点。与野生型相比，cbrA的缺失导致DivK的极地定位率显著降低，这表明CbrA通过调节DivK的磷酸化状态来帮助调节细胞周期过程。与DivK磷酸化和活性假设的下降相一致，我们还发现CtrA的稳定水平增加了inbrA突变体。因此，我们的数据表明，CbrA有助于自由生活的细胞周期调节，这根据其共生的要求，指出了细胞周期调节对于建立有效的宿主相互作用的潜在重要性。
Sinorhizobium melilotiis alternately capable of colonizing the soil as a free-living bacterium or establishing a chronic intracellular infection with its legume host for the purpose of nitrogen fixation. We previously identified theS. melilotitwo-component sensor histidine kinase CbrA as playing an important role in regulating exopolysaccharide production, flagellar motility and symbiosis. Phylogenetic analysis of CbrA has highlighted its evolutionary relatedness to theCaulobacter crescentussensor histidine kinases PleC and DivJ, which are involved in CtrA-dependent cell cycle regulation through the shared response regulator DivK. We therefore became interested in testing whether CbrA plays a role in regulatingS. meliloticell cycle processes. We find the loss ofcbrAresults in filamentous cell growth accompanied by cells that contain an aberrant genome complement, indicating CbrA plays a role in regulating cell division and possibly DNA segregation.S. melilotiDivK localizes to the old cell pole during distinct phases of the cell cycle in a phosphorylation-dependent manner. Loss ofcbrAresults in a significantly decreased rate of DivK polar localization when compared with the wild-type, suggesting CbrA helps regulate cell cycle processes by modulating DivK phosphorylation status as a kinase. Consistent with a presumptive decrease in DivK phosphorylation and activity, we also find the steady-state level of CtrA increased incbrAmutants. Our data therefore demonstrate that CbrA contributes to free-living cell cycle regulation, which in light of its requirement for symbiosis, points to the potential importance of cell cycle regulation for establishing an effective host interaction.