YNMG RNA发夹的折叠热力学与动力学：8-溴鸟苷的特异性掺入通过提高折叠速率导致稳定性增强。

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

作者信息

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

机构信息

Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.

出版信息

Biochemistry. 2004 Nov 9;43(44):14004-14. doi: 10.1021/bi048213e.

DOI:10.1021/bi048213e

PMID:15518549

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 DeltaDeltaG(37)(degrees)= -0.69 +/- 0.15 kcal mol(-1) and DeltaT(M) = +6.8 +/- 1.4 degrees 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 degrees 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.

摘要

修饰核苷酸能够用于探究核酸的基本能量和动力学性质。在此，我们证明了含有核苷酸类似物8-溴鸟苷（8BrG或G）的RNA发夹结构gcUUCGgc相对于未修饰的发夹结构具有更高的稳定性，其ΔΔG(37)(°)= -0.69±0.15 kcal mol(-1)，ΔT(M)= +6.8±1.4℃。核磁共振光谱数据表明，gcUUCGgc稳定性的增强并非源于天然状态；激光温度跳跃实验支持了这一观点，因为gcUUCGgc和gcUUCGgc具有相似的解折叠速率常数，但gcUUCGgc在37.5℃时的折叠速率常数快4.1倍，在等能条件下快2.8倍。基于这些发现，我们提出8BrG降低了变性状态的构象熵，从而加速了对天然状态的构象搜索并增强了稳定性。