Temperature-dependent stability and translation of Escherichia coli ompA mRNA

Abstract

RNase E is known to affect the turnover of ompA mRNA in a growth rate-dependent manner. Here, we show that this enzyme also plays a role in the temperature-dependent stability of the transcript, thereby maintaining comparable levels of OmpA at 28 and 37°C. An increase in the efficiency of RNase E cleavages at 37°C within the 5′ UTR of the transcript in vitro was found to correlate with a decreased half-life and steady-state level at elevated temperature in vivo. However, measurements of de novo OmpA synthesis and in vitro toeprinting experiments suggest that translation of ompA mRNA is more efficient at 37°C when compared to 28°C. Thus, the enhanced translation apparently counteracts the decreased half-life at elevated temperature. Moreover, we propose that the temperature-dependent inverse correlation between ompA mRNA stability and translation can result from structural changes induced in the 5′ UTR of the transcript.