An evolutionary link between sporulation and prophage induction in the structure of a repressor: Anti-repressor complex
An evolutionary link between sporulation and prophage induction in the structure of a repressor: Anti-repressor complex
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DOI：
10.1006/jmbi.1998.2163
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发表时间：
1998-11-13
影响因子：
5.6
通讯作者：
Wilkinson, AJ
中科院分区：
文献类型：
--
作者：
Lewis, RJ;Brannigan, JA;Wilkinson, AJ
孢子形成是某些细菌对逆境的极端反应。在枯草芽孢杆菌中，SIN蛋白，即产孢量抑制区，形成了一个复杂的分子回路，调节产孢量的承诺。SinR是一种四聚体阻遏蛋白，它与进入孢子形成所必需的基因的启动子结合，并阻止它们的转录。这种抑制通过SINI的活性被克服，SINI通过形成SINI-SINR异二聚体来破坏SINR四聚体。在SiI-SinR络合物的晶体结构中揭示了支配这种奇怪的四元相变的相互作用。最令人惊讶和意想不到的发现是，SinR DNA结合区的三级结构与434噬菌体调节裂解/溶原性的阻遏蛋白Ci和Cro的相应结构域相同。这种结构相似性大大超过了SinR与任何细菌蛋白之间的相似性，或者超过了434个抑制子蛋白与其在密切相关的噬菌体lambda中的同源物之间的相似性。SinR和434抑制子的结构所暗示的密切的进化关系引发了对它们功能的比较，以及对两种适应性反应--产孢子形成和原噬菌体诱导之间进化联系的有趣可能性的推测。(C)1998年学术出版社。
Spore formation is an extreme response of some bacteria to adversity. Ln Bacillus subtilis the proteins of the sin, sporulation inhibition, region form a component of an elaborate molecular circuitry that regulates the commitment to sporulation. SinR is a tetrameric repressor protein that binds to the promoters of genes essential for entry into sporulation and prevents their transcription. This repression is overcome through the activity of SinI., which disrupts the SinR tetramer through the formation of a SinI-SinR heterodimer. The interactions governing this curious quaternary transition are revealed in the crystal structure of the SinI-SinR complex. The most striking, and unexpected, finding is that the tertiary structure of the DNA-binding domain of SinR is identical with that of the corresponding domains of the repressor proteins, CI and Cro, of bacteriophage 434 that regulate lysis/lysogeny. This structural similarity greatly exceeds that between SinR and any bacterial protein or between the 434 repressor proteins and their homologues in the closely related bacteriophage lambda. The close evolutionary relationship implied by the structures of SinR and the 434 repressors provokes both comparison of their functions and a speculative consideration of the intriguing possibility of an evolutionary link between the two adaptive responses, sporulation and prophage induction. (C) 1998 Academic Press.