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 degreesC. An increase in the efficiency of RNase E cleavages at 37 degreesC 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 degreesC when compared to 28 degreesC. 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. (C) 2003 Elsevier Inc. All rights reserved.