title: Biophysical properties and thermal stability of oligonucleotides of RNA containing 7,8-dihydro-8-hydroxyadenosine.
abstract: Circular dichroism (CD) was used to assess the stabilization/destabilization imposed by oxidative lesion 7,8-dihydro-8-hydroxyadenosine (8-oxoA) on strands of RNA with different structural motifs. RNA:RNA homoduplex destabilization was observed in a position dependent manner using 10-mers as models that displayed differences between 12.7 and 15.1°C. We found that increasing the number of modifications resulted in depressed Tm values of about 12-15°C per lesion. The same effect was observed on RNA:DNA heteroduplex samples. We also tested the effects of this lesion in short hairpins containing the tetraloop UUCX (X = A, 8-oxoA). We found that the stem was hypersensitive to substitution of A by 8-oxoA and that it destabilized the structure by >23°C. Concomitant substitution at the stem and loop prevented formation of this secondary structure or lead to other less-stable hairpins. Incorporation of this lesion at the first base of the loop had no effect on either structure. Overall, we found that the effects of 8-oxoA on RNA structure are position dependent and that its stabilization may vary from sharp decreases to small increments, in some cases, leading to the formation of other more/less stable structures. These structural changes may have larger biological implications, particularly if the oxidatively modified RNA persists, thus leading to changes in RNA reactivity and function.
authors.affiliation: Department of Chemistry, University of Colorado Denver, Science Building, 1151 Arapahoe St, Denver, CO, 80204.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Chauca-Diaz
authors.forename: Yu Jung
authors.initials: YJ
authors.lastname: Choi
authors.forename: Marino J E
authors.initials: MJ
authors.lastname: Resendiz
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000737:chemistry; D002942:Circular Dichroism; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*
chemical_list: D009841:Oligonucleotides; C036009:8-oxoadenosine; D012313:RNA; D000241:Adenosine
keywords: 8-oxoadenosine; RNA structural changes; circular dichroism; nucleic acid stability; oxidative damage of RNA