The differential stability of the Escherichia coli ompA and bla mRNA at various growth rates is not correlated to the efficiency of translation.

Using two monocistronic gene transcripts, bla and ompA, we have studied the relationship between mRNA stability and translational efficiency. It was found that changes in the ompA mRNA stability are not correlated with an alteration in translational efficiency. In addition, at slow bacterial growth rates, the ompA transcript is translated ten times more efficiently than the bla messenger although the stability of the two transcripts is about equal. At rapid bacterial growth rate, chloramphenicol slightly stabilises both the bla and ompA transcripts without affecting their characteristic difference in half-life. Thus, control of mRNA stability seems not necessarily to be mediated either by the efficiency of loading ribosomes on a transcript, or by the arrest or slowing down of translating ribosomes.