title: Crystal structure of a complex between the phosphorelay protein YPD1 and the response regulator domain of SLN1 bound to a phosphoryl analog.
abstract: The crystal structure of the yeast SLN1 response regulator (RR) domain bound to both a phosphoryl analog [beryllium fluoride (BeF(3)(-))] and Mg(2+), in complex with its downstream phosphorelay signaling partner YPD1, has been determined at a resolution of 1.70 A. Comparisons between the BeF(3)(-)-activated complex and the unliganded (or apo) complex determined previously reveal modest but important differences. The SLN1-R1 x Mg(2+) x BeF(3)(-) structure from the complex provides evidence for the first time that the mechanism of phosphorylation-induced activation is highly conserved between bacterial RR domains and this example from a eukaryotic organism. Residues in and around the active site undergo slight rearrangements in order to form bonds with the essential divalent cation and fluorine atoms of BeF(3)(-). Two conserved switch-like residues (Thr1173 and Phe1192) occupy distinctly different positions in the apo versus BeF(3)(-)-bound structures, consistent with the "Y-T" coupling mechanism proposed for the activation of CheY and other bacterial RRs. Several loop regions and the alpha 4-beta 5-alpha 5 surface of the SLN1-R1 domain undergo subtle conformational changes ( approximately 1-3 A displacements relative to the apo structure) that lead to significant changes in terms of contacts that are formed with YPD1. Detailed structural comparisons of protein-protein interactions in the apo and BeF(3)(-)-bound complexes suggest at least a two-state equilibrium model for the formation of a transient encounter complex, in which phosphorylation of the RR promotes the formation of a phosphotransfer-competent complex. In the BeF(3)(-)-activated complex, the position of His64 from YPD1 needs to be within ideal distance of and in near-linear geometry with Asp1144 from the SLN1-R1 domain for phosphotransfer to occur. The ground-state structure presented here suggests that phosphoryl transfer will likely proceed through an associative mechanism involving the formation of a pentacoordinate phosphorus intermediate.
authors: Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, OK 73019, USA.
authors: Xiaodong
authors: X
authors: Zhao
authors: Daniel M
authors: DM
authors: Copeland
authors: Alexei S
authors: AS
authors: Soares
authors: Ann H
authors: AH
authors: West
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D047908:Intracellular Signaling Peptides and Proteins; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D011494:Protein Kinases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D014867:Water / Q000737:chemistry
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; D014867:Water; D011494:Protein Kinases; C102035:YPD1 protein, S cerevisiae; C083749:SLN1 protein, S cerevisiae