Bick Matthew J, Lamour Valerie, Rajashankar Kanagalaghatta R, Gordiyenko Yuliya, Robinson Carol V, Darst Seth A
The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
J Mol Biol. 2009 Feb 13;386(1):163-77. doi: 10.1016/j.jmb.2008.12.006. Epub 2008 Dec 11.
Entry to sporulation in bacilli is governed by a histidine kinase phosphorelay, a variation of the predominant signal transduction mechanism in prokaryotes. Sda directly inhibits sporulation histidine kinases in response to DNA damage and replication defects. We determined a 2.0-A-resolution X-ray crystal structure of the intact cytoplasmic catalytic core [comprising the dimerization and histidine phosphotransfer domain (DHp domain), connected to the ATP binding catalytic domain] of the Geobacillus stearothermophilus sporulation kinase KinB complexed with Sda. Structural and biochemical analyses reveal that Sda binds to the base of the DHp domain and prevents molecular transactions with the DHp domain to which it is bound by acting as a simple molecular barricade. Sda acts to sterically block communication between the catalytic domain and the DHp domain, which is required for autophosphorylation, as well as to sterically block communication between the response regulator Spo0F and the DHp domain, which is required for phosphotransfer and phosphatase activities.
芽孢杆菌进入孢子形成阶段受组氨酸激酶磷酸化信号转导途径调控，这是原核生物中主要信号转导机制的一种变体。Sda可响应DNA损伤和复制缺陷直接抑制孢子形成组氨酸激酶。我们确定了嗜热栖热放线菌孢子形成激酶KinB与Sda复合的完整细胞质催化核心（由二聚化和组氨酸磷酸转移结构域（DHp结构域）组成，连接到ATP结合催化结构域）的2.0埃分辨率X射线晶体结构。结构和生化分析表明，Sda结合到DHp结构域的基部，并通过充当简单的分子屏障来阻止与其结合的DHp结构域进行分子相互作用。Sda在空间上阻止催化结构域与DHp结构域之间的通信，这是自磷酸化所必需的，同时在空间上也阻止响应调节因子Spo0F与DHp结构域之间的通信，这是磷酸转移和磷酸酶活性所必需的。
