Temperature-controlled structural alterations of an RNA thermometer

Research output: Contribution to journalArticle

Abstract

Thermoresponsive structures in the 5'-untranslated region of mRNA are known to control translation of heat shock and virulence genes. Expression of many rhizobial heat shock genes is regulated by a conserved sequence element called ROSE for repression of heat shock gene expression. This cis-acting, untranslated mRNA is thought to prevent ribosome access at low temperature through an extended secondary structure, which partially melts when the temperature rises. We show here by a series of in vivo and in vitro approaches that ROSE is a sensitive thermometer responding in the physiologically relevant temperature range between 30 and 40 degrees C. Point mutations predicted to disrupt base pairing enhanced expression at 30 degrees C. Compensatory mutations restored repression, emphasizing the importance of secondary structures in the sensory RNA. Only moderate inducibility of a 5'-truncated ROSE variant suggests that interactions between individual stem loops coordinate temperature sensing. In the presence of a complementary oligonucleotide, the functionally important stem loop of ROSE was rendered susceptible to RNase H treatment at heat shock temperatures. Since major structural rearrangements were not observed during UV and CD spectroscopy, subtle structural changes involving the Shine-Dalgarno sequence are proposed to mediate translational control. Temperature perception by the sensory RNA is an ordered process that most likely occurs without the aid of accessory factors.

Details

Authors
External organisations
  • ETH Zürich
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biochemistry and Molecular Biology

Keywords

  • 5' Untranslated Regions, Bradyrhizobium/genetics, Circular Dichroism, Computer Simulation, Escherichia coli/genetics, Hot Temperature, Mutation, Nucleic Acid Conformation, Oligonucleotides/chemistry, Point Mutation, Protein Biosynthesis, RNA/chemistry, RNA, Messenger/metabolism, Ribonuclease H/metabolism, Spectrophotometry, Temperature, Transcription, Genetic, Ultraviolet Rays, beta-Galactosidase/metabolism
Original languageEnglish
Pages (from-to)47915-47921
Number of pages7
JournalJournal of Biological Chemistry
Volume278
Issue number48
Publication statusPublished - 2003 Nov 28
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes