title: A chemical approach for site-specific identification of NMR signals from protein side-chain NH₃⁺ groups forming intermolecular ion pairs in protein-nucleic acid complexes.
abstract: Protein-nucleic acid interactions involve intermolecular ion pairs of protein side-chain and DNA or RNA phosphate groups. Using three protein-DNA complexes, we demonstrate that site-specific oxygen-to-sulfur substitution in phosphate groups allows for identification of NMR signals from the protein side-chain NH3 (+) groups forming the intermolecular ion pairs. A characteristic change in their (1)H and (15)N resonances upon this modification (i.e., substitution of phosphate to phosphorodithioate) can represent a signature of an intermolecular ion pair. Hydrogen-bond scalar coupling between protein side-chain (15)N and DNA phosphorodithiaote (31)P nuclei provides direct confirmation of the intermolecular ion pair. The same approach is likely applicable to protein-RNA complexes as well.
authors.affiliation: Department of NanoMedicine and Biomedical Engineering and Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, 77225, USA.
authors.forename: Kurtis M
authors.initials: KM
authors.lastname: Anderson
authors.forename: Dan
authors.initials: D
authors.lastname: Nguyen
authors.forename: Alexandre
authors.initials: A
authors.lastname: Esadze
authors.forename: Levani
authors.initials: L
authors.lastname: Zandrashvili
authors.forename: David G
authors.initials: DG
authors.lastname: Gorenstein
authors.forename: Junji
authors.initials: J
authors.lastname: Iwahara
mesh_terms: D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011506:Proteins / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*
chemical_list: D011506:Proteins; D012313:RNA; D004247:DNA