State Key Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, Yunnan, China.
Yunnan Institute of Tropical Crops, Jinghong, Yunnan, China.
Microbiologyopen. 2018 Jun;7(3):e00566. doi: 10.1002/mbo3.566. Epub 2018 Jan 3.
Bacillus subtilis responds to environmental stress cues and develops endospores for survival. In the process of endospore formation, sporulation initiation is a vital stage and this stage is governed by autophosphorylation of the sensor histidine kinases. The second major sensor kinase KinB perceives the intracellular changes of GTP and ATP during sporulation. However, determination of the environmental signals as well as its related signaling pathway of KinB requires further elucidation. Our current study found that, contrary to the sporulation failure induced by ΔkinA in the nutrient-rich 2× SG medium, the sensor kinase KinB sensed the environmental cues in the nutrient-poor MM medium. Two other membrane proteins, KapB and KbaA, also responded similarly to the same external signal as KinB. Both KapB and KbaA acted upstream of KinB, but they exerted their regulation upon KinB independently. Furthermore, we demonstrated that both the SH3 domain and the α-helix structure in KapB are required for sensing or transducing the signal of sporulation initiation. Collectively, our work here supplied the direct evidences that KinB and its pathway sense the external signal of nutrient starvation in MM medium, and further analyzes the interrelationship among KinB, KbaA, and KapB.
枯草芽孢杆菌会对环境压力信号做出响应，并产生芽孢以求得生存。在芽孢形成的过程中，芽孢的起始是一个关键的阶段，这一阶段是由传感器组氨酸激酶的自动磷酸化来调控的。第二个主要的传感器激酶 KinB 在孢子形成过程中感知细胞内 GTP 和 ATP 的变化。然而，KinB 的环境信号及其相关信号通路的确定需要进一步阐明。我们目前的研究发现，与在富含营养的 2×SG 培养基中因ΔkinA 引起的孢子形成失败相反，传感器激酶 KinB 在营养贫乏的 MM 培养基中感知环境信号。另外两种膜蛋白 KapB 和 KbaA 也对与 KinB 相同的外部信号做出类似的响应。KapB 和 KbaA 都位于 KinB 的上游，但它们对 KinB 的调控是独立的。此外，我们证明了 KapB 的 SH3 结构域和 α-螺旋结构对于感知或转导起始孢子形成的信号是必需的。总之，我们的工作提供了直接的证据，证明 KinB 及其途径可以感知 MM 培养基中营养饥饿的外部信号，并进一步分析了 KinB、KbaA 和 KapB 之间的相互关系。
