Thermodynamics of RNA melting, one base pair at a time.

Published

Journal Article

The melting of base pairs is a ubiquitous feature of RNA structural transitions, which are widely used to sense and respond to cellular stimuli. A recent study employing solution nuclear magnetic resonance (NMR) imino proton exchange spectroscopy provides a rare base-pair-specific view of duplex melting in the Salmonella FourU RNA thermosensor, which regulates gene expression in response to changes in temperature at the translational level by undergoing a melting transition. The authors observe "microscopic" enthalpy-entropy compensation--often seen "macroscopically" across a series of related molecular species--across base pairs within the same RNA. This yields variations in base-pair stabilities that are an order of magnitude smaller than corresponding variations in enthalpy and entropy. A surprising yet convincing link is established between the slopes of enthalpy-entropy correlations and RNA melting points determined by circular dichroism (CD), which argues that unfolding occurs when base-pair stabilities are equalized. A single AG-to-CG mutation, which enhances the macroscopic hairpin thermostability and folding cooperativity and renders the RNA thermometer inactive in vivo, spreads its effect microscopically throughout all base pairs in the RNA, including ones far removed from the site of mutation. The authors suggest that an extended network of hydration underlies this long-range communication. This study suggests that the deconstruction of macroscopic RNA unfolding in terms of microscopic unfolding events will require careful consideration of water interactions.

Full Text

Duke Authors

Cited Authors

  • Nikolova, EN; Al-Hashimi, HM

Published Date

  • September 2010

Published In

Volume / Issue

  • 16 / 9

Start / End Page

  • 1687 - 1691

PubMed ID

  • 20660079

Pubmed Central ID

  • 20660079

Electronic International Standard Serial Number (EISSN)

  • 1469-9001

Digital Object Identifier (DOI)

  • 10.1261/rna.2235010

Language

  • eng

Conference Location

  • United States