Folding thermodynamics and kinetics of YNMG RNA hairpins: Specific incorporation of 8-bromoguanosine leads to stabilization by enhancement of the folding rate

David J. Proctor, Hairong Ma, Elzbieta Kierzek, Ryszard Kierzek, Martin Gruebele, Philip C. Bevilacqua

Research output: Contribution to journalArticlepeer-review

Abstract

Modified nucleotides allow fundamental energetic and kinetic properties of nucleic acids to be probed. Here, we demonstrate that an RNA hairpin containing the nucleotide analogue 8-bromoguanosine (8BrG or G), gcUUCGgc, has enhanced stability relative to the unmodified hairpin, with ΔΔG 37° = -0.69 ± 0.15 kcal mol-1 and ΔTM = +6.8 ± 1.4°C. NMR spectroscopic data suggest that the enhanced stability of gcUUCGgc does not arise from the native state; laser temperature-jump experiments support this notion, as gcUUCGgc and gcUUCGgc have similar unfolding rate constants, but the folding rate constant of gcUUCGgc is 4.1-fold faster at 37.5°C and 2.8-fold faster under isoenergetic conditions. On the basis of these findings, we propose that 8BrG reduces the conformational entropy of the denatured state, resulting in an accelerated conformational search for the native state and enhanced stability.

Original languageEnglish (US)
Pages (from-to)14004-14014
Number of pages11
JournalBiochemistry
Volume43
Issue number44
DOIs
StatePublished - Nov 9 2004

ASJC Scopus subject areas

  • Biochemistry

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