title: Sequence-dependent variations in the 31P NMR spectra and backbone torsional angles of wild-type and mutant Lac operator fragments.
abstract: Assignment of the 31P resonances of a series of six sequenced-related tetradecamer DNA duplexes, d(TGTGAGCGCTCACA)2, d(TATGAGCGCTCATA)2, d(TCTGAGCGCTCAGA)2, d(TGTGTGCGCACACA)2, d(TGTGACGCGTCACA)2 and d(CACAGTATACTGTG)2, related to the lac operator DNA sequence was determined either by site-specific 17O labeling of the phosphoryl groups or by two-dimensional 1H-31P pure absorption phase constant time (PAC) heteronuclear correlation spectroscopy. J(H3'-P) coupling constants for each of the phosphates of the tetradecamers were obtained from 1H-31P J-resolved selective proton flip 2D spectra. By use of a modified Karplus relationship the C4'-C3'-O3'-P torsional angles (epsilon) were obtained. Comparison of the 31P chemical shifts and J(H3'-P) coupling constants of these sequences has allowed greater insight into those various factors responsible for 31P chemical shift variations in oligonucleotides and provided an important probe of the sequence-dependent structural variation of the deoxyribose phosphate backbone of DNA in solution. These sequence-specific variations in the conformation of the DNA sugar phosphate backbone of various lac operator DNA sequences can possibly explain the sequence-specific recognition of DNA by DNA binding proteins, as mediated through direct contacts between the phosphates and the protein.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907.
authors.forename: S A
authors.initials: SA
authors.lastname: Schroeder
authors.forename: V
authors.initials: V
authors.lastname: Roongta
authors.forename: J M
authors.initials: JM
authors.lastname: Fu
authors.forename: C R
authors.initials: CR
authors.lastname: Jones
authors.forename: D G
authors.initials: DG
authors.lastname: Gorenstein
mesh_terms: D001483:Base Sequence; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004247:DNA; D007763:Lac Operon; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009841:Oligonucleotides; D009875:Operator Regions, Genetic
chemical_list: D046911:Macromolecular Substances; D009841:Oligonucleotides; D004247:DNA