Campbell Elizabeth A, Masuda Shoko, Sun Jing L, Muzzin Oriana, Olson C Anders, Wang Sheng, Darst Seth A
The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Cell. 2002 Mar 22;108(6):795-807. doi: 10.1016/s0092-8674(02)00662-1.
Cell type-specific transcription during Bacillus sporulation is established by sigmaF. SpoIIAB is an anti-sigma that binds and negatively regulates sigmaF, as well as a serine kinase that phosphorylates and inactivates the anti-anti-sigma SpoIIAA. The crystal structure of sigmaF bound to the SpoIIAB dimer in the low-affinity, ADP form has been determined at 2.9 A resolution. SpoIIAB adopts the GHKL superfamily fold of ATPases and histidine kinases. A domain of sigmaF contacts both SpoIIAB monomers, while 80% of the sigma factor is disordered. The interaction occludes an RNA polymerase binding surface of sigmaF, explaining the SpoIIAB anti-sigma activity. The structure also explains the specificity of SpoIIAB for its target sigma factors and, in combination with genetic and biochemical data, provides insight into the mechanism of SpoIIAA anti-anti-sigma activity.
芽孢杆菌形成芽孢过程中的细胞类型特异性转录由σF建立。SpoIIAB是一种抗σ因子，它结合并负向调节σF，同时它也是一种丝氨酸激酶，可磷酸化并使抗抗σ因子SpoIIAA失活。已在2.9埃分辨率下确定了以低亲和力ADP形式与SpoIIAB二聚体结合的σF的晶体结构。SpoIIAB采用ATP酶和组氨酸激酶的GHKL超家族折叠结构。σF的一个结构域与SpoIIAB的两个单体都有接触，而80%的σ因子是无序的。这种相互作用封闭了σF的RNA聚合酶结合表面，解释了SpoIIAB的抗σ因子活性。该结构还解释了SpoIIAB对其靶标σ因子的特异性，并结合遗传和生化数据，深入了解了SpoIIAA抗抗σ因子活性的机制。
