RNA switches out in the cold

Abstract

In this issue of Molecular Cell, Giuliodori et al. (2010) describe a cold-induced genetic switch made of RNA. Could thermo-sensing RNAs be among the most common types of RNA genetic switches?

Figure 1. Alternative structures formed by a mRNA for a cold-induced gene

(A) At 37°C, newly transcribed cspA mRNAs form a secondary structure wherein most of 5′ UTR interacts with nucleotides from the coding region. This resulting structure sequesters both the SD and AUG sequences in strong base-paired stems. (B) At 10°C, cspA mRNA transcripts adopt an almost entirely different secondary structure that present nucleotides of the ribosome binding site or SD sequence (blue) in the loop of a hairpin, while the AUG start codon (green) resides in a weak hairpin. A short pseudoknot (orange) is part of the complex structure formed by the first ~120 nucleotides of the 5′ UTR, which could be a key component of the RNA thermometer. Red boxes identify the only hairpin in the translation initiation region shared by the two structural forms. Not depicted are the 3′ portions (dashed lines) of the 428-nucleotide mRNA that also undergo temperature-mediated structure modulation.