Question

What is an RNA thermometer?

Answer 1

An RNA thermometer is a temperature sensitive non coding RNA molecules which are located in 5' Untranslated Region (5' UTR) of messenger RNA (mRNA) encoding heat shock proteins.

They are mostly present in prokaryotes but also present in some of eukaryotes and human (rare).

RNA thermometer regulates gene expression either during heat shock or cold shock response. When there is either heat shock or cold shock there is secondary structural change in the RNA thermometer. This change can either expose or occlude important RNA sites ( e.g. Ribosomal binding site) affecting translation rate of a protein coding gene.

Functions of RNA thermometer:-

• Temperature dependent regulation of RNA molecules.
• Pathogenicity.
• Regulation of gene expression.

Examples-

• FourU
• Lig RNA thermometer
• Heat Shock RNA 1 (HSR 1).

Mechanism of Heat shock RNA 1:-

When cell temperature exceedes 37° C

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Thermosensor HSR 1 activates heat shock transcription factor 1 (HSF 1).

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Induction of protective proteins and thus preventing cell from overheating.