Yeast temperature-sensitive mutants specifically impaired in processing of poly(A)-containing RNAs.

The selection at 22 degrees C of yeast cordycepin (3'-deoxyadenosine) sensitive mutants which would be temperature-sensitive at 37 degrees C allowed the obtention of mutants specifically impaired in processing of Poly(A)-containing RNAs at 37 degrees C. The mutants displaying this phenotype belong to two different loci. The biochemical study of the physiological function which is blocked by the mutation has revealed that the level of radioactive Poly(A)-containing RNAs found in a 5 min pulse after a 10 min shift at 37 degrees C is 6 times less in the mutants than in the wild type without reduction of the non Poly(A)-containing RNAs fraction. Further studies have shown no alteration in the two Poly(A) polymerases activities and suggest strongly a faster decay of Poly(A)-containing RNAs in the mutants.