Bordes Patricia, Wigneshweraraj Siva R, Schumacher Jörg, Zhang Xiaodong, Chaney Matthew, Buck Martin
Department of Biological Sciences, Sir Alexander Fleming Building, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.
Proc Natl Acad Sci U S A. 2003 Mar 4;100(5):2278-83. doi: 10.1073/pnas.0537525100. Epub 2003 Feb 24.
Members of the protein family called ATPases associated with various cellular activities (AAA(+)) play a crucial role in transforming chemical energy into biological events. AAA(+) proteins are complex molecular machines and typically form ring-shaped oligomeric complexes that are crucial for ATPase activity and mechanism of action. The Escherichia coli transcription activator phage shock protein F (PspF) is an AAA(+) mechanochemical enzyme that functions to sense and relay the energy derived from nucleoside triphosphate hydrolysis to catalyze transcription by the sigma(54)-RNA polymerase. Closed promoter complexes formed by the sigma(54)-RNA polymerase are substrates for the action of PspF. By using a protein fragmentation approach, we identify here at least one sigma(54)-binding surface in the PspF AAA(+) domain. Results suggest that ATP hydrolysis by PspF is coupled to the exposure of at least one sigma(54)-binding surface. This nucleotide hydrolysis-dependent presentation of a substrate binding surface can explain why complexes that form between sigma(54) and PspF are transient and could be part of a mechanism used generally by other AAA(+) proteins to regulate activity.
被称为与各种细胞活动相关的ATP酶（AAA(+)）的蛋白质家族成员，在将化学能转化为生物事件的过程中发挥着关键作用。AAA(+)蛋白是复杂的分子机器，通常形成环状寡聚复合物，这对于ATP酶活性和作用机制至关重要。大肠杆菌转录激活因子噬菌体休克蛋白F（PspF）是一种AAA(+)机械化学酶，其功能是感知并传递来自核苷三磷酸水解的能量，以催化σ(54)-RNA聚合酶进行转录。由σ(54)-RNA聚合酶形成的封闭启动子复合物是PspF作用的底物。通过使用蛋白质片段化方法，我们在此确定了PspF的AAA(+)结构域中至少一个与σ(54)结合的表面。结果表明，PspF的ATP水解与至少一个与σ(54)结合表面的暴露相关联。这种依赖于核苷酸水解的底物结合表面的呈现，可以解释为什么σ(54)和PspF之间形成的复合物是短暂的，并且可能是其他AAA(+)蛋白普遍用于调节活性的机制的一部分。
