Polynucleotide phosphorylase can participate in decay of mRNA in Escherichia coli in the absence of ribonuclease II.

In a mutant strain defective in polynucleotide phosphorylase, under conditions where the enzyme becomes limiting, it is possible to demonstrate that chemical as well as functional half lives of mRNA become longer if the strain is also missing ribonuclease II. These results allow to unify in a simple model a variety of observations about turnover of RNA in a variety of bacteria.