title: Water-mediated interactions in the CRP-cAMP-DNA complex: does water mediate sequence-specific binding at the DNA primary-kink site?
abstract: The cyclic AMP receptor protein (CRP) of Escherichia coli binds preferentially to DNA sequences possessing a T:A base pair at position 6 (at which the DNA becomes kinked), but with which it does not form any direct interactions. It has been proposed that indirect readout is involved in CRP-DNA binding, in which specificity for this base pair is primarily related to sequence effects on the energetic susceptibility of the DNA to kink formation. In the current study, the possibility of contributions to indirect readout by water-mediated hydrogen bonding of CRP with the T:A base pair was investigated. A 1.0 ns molecular dynamics simulation of the CRP-cAMP-DNA complex in explicit solvent was performed, and assessed for water-mediated CRP-DNA hydrogen bonds; results were compared to several X-ray crystal structures of comparable complexes. While several water-mediated CRP-DNA hydrogen bonds were identified, none of these involved the T:A base pair at position 6. Therefore, the sequence specificity for this base pair is not likely enhanced by water-mediated hydrogen bonding with the CRP.
authors: Department of Chemistry and Centre for Biotechnology, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada.
authors: Bryan M B
authors: BM
authors: VanSchouwen
authors: Heather L
authors: HL
authors: Gordon
authors: Stuart M
authors: SM
authors: Rothstein
authors: Yuto
authors: Y
authors: Komeiji
authors: Kaori
authors: K
authors: Fukuzawa
authors: Shigenori
authors: S
authors: Tanaka
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D019295:Computational Biology / Q000379:methods; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D000242:Cyclic AMP / Q000737:chemistry*; D004269:DNA, Bacterial / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D008954:Models, Biological; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D011953:Receptors, Cyclic AMP / Q000737:chemistry*; D013379:Substrate Specificity; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D011953:Receptors, Cyclic AMP; C047947:cyclic AMP receptor protein, E coli; D014867:Water; D000242:Cyclic AMP