title: SAS solution structures of the apo and Mg2+/BeF3(-)-bound receiver domain of DctD from Sinorhizobium meliloti.
abstract: Two-component signal transduction is the predominant information processing mechanism in prokaryotes and is also present in single-cell eukaryotes and higher plants. A phosphorylation-based switch is commonly used to activate as many as 40 different types of output domains in more than 6000 two-component response regulators that can be identified in the sequence databases. Previous biochemical and crystallographic studies showed that phosphorylation of the two-component receiver domain of DctD causes a switch between alternative dimeric forms, but it was unclear from the crystal lattice of the activated protein precisely which of four possible dimeric configurations is the biologically relevant one [Park, S., et al. (2002) FASEB J. 16, 1964-1966]. Here we report solution structures of the apo and activated DctD receiver domain derived from small angle scattering data. The apo dimer closely resembles that seen in the crystal structure, and the solution data for the activated protein eliminate two of the possible four dimeric conformations seen in the crystal lattice and strongly implicate one as the biologically relevant structure. These results corroborate the previously proposed model for how receiver domains regulate their downstream AAA+ ATPase domains.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. btn1@psu.edu
authors.forename: B Tracy
authors.initials: BT
authors.lastname: Nixon
authors.forename: Hemant P
authors.initials: HP
authors.lastname: Yennawar
authors.forename: Michaeleen
authors.initials: M
authors.lastname: Doucleff
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Pelton
authors.forename: David E
authors.initials: DE
authors.lastname: Wemmer
authors.forename: Susan
authors.initials: S
authors.lastname: Krueger
authors.forename: Elena
authors.initials: E
authors.lastname: Kondrashkina
mesh_terms: D001608:Beryllium / Q000737:chemistry*; D019281:Dimerization; D005459:Fluorides / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D010766:Phosphorylation; D011487:Protein Conformation; D016962:Sinorhizobium meliloti / Q000737:chemistry*
chemical_list: C035982:beryllium fluoride; D008274:Magnesium; D001608:Beryllium; D005459:Fluorides