A new role for RNase II in mRNA decay: Striking differences between RNase II mutants and similarities with a strain deficient in RNase E

Abstract

The effect of Escherichia coli ribonuclease II and polynucleotide phosphorylase was analysed on the degradation of Desulfovibrio vulgaris cytochrome c 3 ( cyc) mRNA. In the absence of these exoribonucleolytic activities, cyc mRNA was stabilised but the two enzymes had a different role in its decay. Surprisingly, a temperature-sensitive mutation in ribonuclease II gave a degradation pattern similar to what had been observed in the absence of endoribonuclease E activity. In an RNase II deletion mutant this was not observed. We propose and verify a model in which the temperature-sensitive ribonuclease II interferes with the action of ribonuclease E.