期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2010
卷号：107
期号：20
页码：9376-9381
DOI：10.1073/pnas.1001188107
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：ATP hydrolysis-dependent molecular machines and motors often drive regulated conformational transformations in cell signaling and gene regulation complexes. Conformational reorganization of a gene regulation complex containing the major variant form of bacterial RNA polymerase (RNAP), E{sigma}54, requires engagement with its cognate ATP-hydrolyzing activator protein. Importantly, this activated RNAP is essential for a number of adaptive responses, including those required for bacterial pathogenesis. Here we characterize the initial encounter between the enhancer-dependent E{sigma}54 and its cognate activator AAA+ ATPase protein, before ADP+Pi formation, using a small primed RNA (spRNA) synthesis assay. The results show that in a prehydrolysis state, sufficient activator-dependent rearrangements in E{sigma}54 have occurred to allow engagement of the RNAP active site with single-stranded promoter DNA to support spRNA synthesis, but not to melt the promoter DNA. This catalytically competent transcription intermediate has similarity with the open promoter complex, in that the RNAP dynamics required for DNA scrunching should be occurring. Significantly, this work highlights that prehydrolysis states of ATPases are functionally important in the molecular transformations they drive.
关键词：transcription initiation ; sigma factors ; ATP analogues ; DNA melting
