A NEW ROLE FOR RNASE-II IN MESSENGER-RNA DECAY - STRIKING DIFFERENCESBETWEEN RNASE-II MUTANTS AND SIMILARITIES WITH A STRAIN DEFICIENT IN RNASE-E

The effect of Escherichia call ribonuclease II and polynucleotide phos phorylase was analysed on the degradation-of Desulfovibrio vulgaris cy tochrome cs (eye) mRNA. In the absence of these exoribonucleolytic act ivities, eye mRNA was stabilised but the two enzymes had a different r ole in its decay. Surprisingly,a temperature-sensitive mutation in rib onuclease II gave a degradation pattern similar to what had been obser ved in the absence of endoribonuclease E activity, In an RNase II dele tion mutant this was not observed. We propose and verify a model in wh ich the temperature-sensitive ribonuclease II interferes with the acti on of ribonuclease E.