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：2008
卷号：105
期号：9
页码：3292-3297
DOI：10.1073/pnas.0709513105
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We recently proposed that a nontemplate strand base in the discriminator region of bacterial promoters, the region between the -10 element and the transcription start site, makes sequence-specific contacts to region 1.2 of the {sigma} subunit of Escherichia coli RNA polymerase (RNAP). Because rRNA promoters contain sequences within the discriminator region that are suboptimal for interaction with {sigma}1.2, these promoters have the kinetic properties required for regulation by the RNAP-binding factors DksA and ppGpp. Here, we use zero-length cross-linking and mutational, kinetic, and footprinting studies to map RNAP interactions with the nontemplate strand bases at the junction of the -10 element and the discriminator region in an unregulated rRNA promoter variant and in the {lambda}PR promoter. Our studies indicate that nontemplate strand bases adjacent to the -10 element bind within a 9-aa interval in {sigma}1.2 (residues 99-107). We also demonstrate that the downstream-most base on the nontemplate strand of the -10 hexamer cross-links to {sigma} region 2, and not to {sigma}1.2. Our results refine models of RNAP-DNA interactions in the promoter complex that are crucial for regulation of transcription initiation.
关键词：promoter element ; RNA polymerase ; transcription initiation ; discriminator region ; −10 element
