title: DNase I-tRNA interaction.
abstract: Deoxyribonuclease I (DNase I) binds right-handed DNA duplex via a minor groove and the backbone phosphate group with no contact to the major groove. It hydrolyses double-stranded DNA predominantly by a single-stranded nicking mechanism under physiological conditions, in the presence of divalent Mg and Ca cations. Even though DNase-RNA interaction was observed, less is known about the protein-RNA binding mode and the effect of such complexation on both protein and RNA conformations. The aim of this study was to examine the effects of DNase I-tRNA interaction on tRNA and protein conformations. The interaction of DNase I with tRNA is monitored under physiological conditions, in the absence of Mg2+, using constant DNA concentration of 12.5 mM (phosphate) and various protein contents (10 microM to 250 microM). FTIR, UV-visible, and CD spectroscopic methods were used to analyze the protein binding mode, the binding constant, and the effects of polynucleotide-enzyme interaction on both tRNA and protein conformations. Spectroscopic evidence showed major DNase-PO2 and minor groove interactions with overall binding constant of K = 2.1 (+/-0.7) x 10(4) M(-1). The DNase I-tRNA interaction alters protein secondary structure with major reduction of the alpha-helix, and increases the random coil, beta-anti and turn structures, while tRNA remains in the A-conformation. No digestion of tRNA by DNase I was observed in the protein-tRNA complexes.
authors.affiliation: Department of Chemistry-Biology, University of Québec at Trois-Rivières, Trois-Rivières (Québec) Canada G9A 5H7.
authors.forename: C N
authors.initials: CN
authors.lastname: N'soukpoé-Kossi
authors.forename: H A
authors.initials: HA
authors.lastname: Tajmir-Riahi
mesh_terms: D002942:Circular Dichroism; D003850:Deoxyribonuclease I / Q000737:chemistry / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D017433:Protein Structure, Secondary; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D012343:RNA, Transfer; D003850:Deoxyribonuclease I