Dago Angel Ernesto, Wigneshweraraj Siva R, Buck Martin, Morett Enrique
Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos 62210, México.
J Biol Chem. 2007 Jan 12;282(2):1087-97. doi: 10.1074/jbc.M608715200. Epub 2006 Nov 6.
Transcription from sigma54-dependent bacterial promoters can be regarded as a second paradigm for bacterial gene transcription. The initial sigma54-RNA polymerase (RNAP).promoter complex, the closed complex, is transcriptionally silent. The transcriptionally proficient sigma54-RNAP.promoter complex, the open complex, is formed upon remodeling of the closed complex by actions of a specialized activator protein that belongs to the AAA (ATPases associated with various cellular activities) protein family in an ATP hydrolysis-dependent reaction. The integrity of a highly conserved signature motif in the AAA activator (known as the GAFTGA motif) is important for the remodeling activity of the AAA activator and for open complex formation. We now provide evidence that the invariant threo-nine residue of the GAFTGA motif plays a role in sensing the DNA downstream of the sigma54-RNAP-binding site and in coupling this information to sigma54-RNAP via the conserved regulatory Region I domain of sigma54 during open complex formation.
来自σ54依赖型细菌启动子的转录可被视为细菌基因转录的第二种模式。最初的σ54-RNA聚合酶（RNAP）-启动子复合物，即封闭复合物，在转录上是沉默的。具有转录活性的σ54-RNAP-启动子复合物，即开放复合物，是在一种属于AAA（与各种细胞活动相关的ATP酶）蛋白家族的特殊激活蛋白的作用下，通过ATP水解依赖性反应对封闭复合物进行重塑而形成的。AAA激活蛋白中一个高度保守的特征基序（称为GAFTGA基序）的完整性对于AAA激活蛋白的重塑活性和开放复合物的形成很重要。我们现在提供证据表明，GAFTGA基序中不变的苏氨酸残基在开放复合物形成过程中，在感知σ54-RNAP结合位点下游的DNA以及通过σ54保守的调控区域I结构域将该信息与σ54-RNAP偶联方面发挥作用。
