Title: Three-dimensional EM structure of an intact activator-dependent transcription initiation complex. | Journal: Proceedings of the National Academy of Sciences of the United States of America. 2009 Nov;106(47):19830-5 | Authors: Hudson BP, Quispe J, Lara-González S, Kim Y, Berman HM, Arnold E, Ebright RH, Lawson CL. | Abstract: We present the experimentally determined 3D structure of an intact activator-dependent transcription initiation complex comprising the Escherichia coli catabolite activator protein (CAP), RNA polymerase holoenzyme (RNAP), and a DNA fragment containing positions -78 to +20 of a Class I CAP-dependent promoter with a CAP site at position -61.5 and a premelted transcription bubble. A 20-A electron microscopy reconstruction was obtained by iterative projection-based matching of single particles visualized in carbon-sandwich negative stain and was fitted using atomic coordinate sets for CAP, RNAP, and DNA. The structure defines the organization of a Class I CAP-RNAP-promoter complex and supports previously proposed interactions of CAP with RNAP alpha subunit C-terminal domain (alphaCTD), interactions of alphaCTD with sigma(70) region 4, interactions of CAP and RNAP with promoter DNA, and phased-DNA-bend-dependent partial wrapping of DNA around the complex. The structure also reveals the positions and shapes of species-specific domains within the RNAP beta', beta, and sigma(70) subunits. | See full PubMed entry: http://www.ncbi.nlm.nih.gov/pubmed/19903881 |
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