title: ATP ground- and transition states of bacterial enhancer binding AAA+ ATPases support complex formation with their target protein, sigma54.
abstract: Transcription initiation by the sigma54 form of bacterial RNA polymerase requires hydrolysis of ATP by an enhancer binding protein (EBP). We present SAS-based solution structures of the ATPase domain of the EBP NtrC1 from Aquifex aeolicus in different nucleotide states. Structures of apo protein and that bound to AMPPNP or ADP-BeF(x) (ground-state mimics), ADP-AlF(x) (a transition-state mimic), or ADP (product) show substantial changes in the position of the GAFTGA loops that contact polymerase, particularly upon conversion from the apo state to the ADP-BeF(x) state, and from the ADP-AlF(x) state to the ADP state. Binding of the ATP analogs stabilizes the oligomeric form of the ATPase and its binding to sigma54, with ADP-AlF(x) having the largest effect. These data indicate that ATP binding promotes a conformational change that stabilizes complexes between EBPs and sigma54, while subsequent hydrolysis and phosphate release drive the conformational change needed to open the polymerase/promoter complex.
authors: Integrative Biosciences Graduate Degree Program, Chemical Biology, The Pennsylvania State University, University Park, PA 16802, USA.
authors: Baoyu
authors: B
authors: Chen
authors: Michaeleen
authors: M
authors: Doucleff
authors: David E
authors: DE
authors: Wemmer
authors: Sacha
authors: S
authors: De Carlo
authors: Hector H
authors: HH
authors: Huang
authors: Eva
authors: E
authors: Nogales
authors: Timothy R
authors: TR
authors: Hoover
authors: Elena
authors: E
authors: Kondrashkina
authors: Liang
authors: L
authors: Guo
authors: B Tracy
authors: BT
authors: Nixon
mesh_terms: D000251:Adenosine Triphosphatases / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D001419:Bacteria / Q000201:enzymology*; D004742:Enhancer Elements, Genetic; D051877:RNA Polymerase Sigma 54 / Q000378:metabolism*; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D000255:Adenosine Triphosphate; D051877:RNA Polymerase Sigma 54; D000251:Adenosine Triphosphatases