Elderkin Sarah, Jones Susan, Schumacher Jörg, Studholme David, Buck Martin
Department of Biological Sciences, Imperial College of Science Technology and Medicine, Biomedical Sciences Building, Imperial College Road, London SW7 2AZ, UK.
J Mol Biol. 2002 Jun 28;320(1):23-37. doi: 10.1016/S0022-2836(02)00404-7.
The PspA protein, a negative regulator of the Escherichia coli phage shock psp operon, is produced when virulence factors are exported through secretins in many Gram-negative pathogenic bacteria and its homologue in plants, VIPP1, plays a critical role in thylakoid biogenesis, essential for photosynthesis. Activation of transcription by the enhancer-dependent bacterial sigma(54) containing RNA polymerase occurs through ATP hydrolysis-driven protein conformational changes enabled by activator proteins that belong to the large AAA(+) mechanochemical protein family. We show that PspA directly and specifically acts upon and binds to the AAA(+) domain of the PspF transcription activator. Interactions involving PspF and nucleotide are changed by the action of PspA. These changes and the complexes that form between PspF and PspA can explain how PspA exerts its negative effects upon transcription activated by PspF, and are of significance when considering how activities of other AAA(+) proteins might be controlled.
PspA蛋白是大肠杆菌噬菌体休克psp操纵子的负调控因子，当毒力因子通过许多革兰氏阴性病原菌中的分泌素输出时产生，其在植物中的同源物VIPP1在类囊体生物发生中起关键作用，而类囊体生物发生对光合作用至关重要。由依赖增强子的含细菌σ因子（54）的RNA聚合酶激活转录是通过ATP水解驱动的蛋白质构象变化实现的，这种变化由属于大型AAA（+）机械化学蛋白家族的激活蛋白促成。我们发现，PspA直接且特异性地作用于并结合PspF转录激活因子的AAA（+）结构域。PspA的作用改变了涉及PspF和核苷酸的相互作用。这些变化以及PspF和PspA之间形成的复合物可以解释PspA如何对PspF激活的转录产生负面影响，并且在考虑如何控制其他AAA（+）蛋白的活性时具有重要意义。
