Size and turnover of polyadenylic acid-containing ribonucleic acids in a fragile mutant of Saccharomyces cerevisiae

Abstract

RNA-containing polyadenylic acid [poly(A)+-RNA] was studied in lysates from an osmotic-sensitive mutant of S. cerevisiae characterized by low nuclease activity. The poly(A)+-RNA fraction, analyzed by electrophoresis in polyacrylamide-formamide gels, constitutes a heterogeneous population of molecules, with MW ranging from 0.2 .times. 106 to 3 .times. 106 and having an average of 1.2 .times. 106. The turnover rate of poly(A)+-RNA was determined by the decay of radioactivity after a cold uracil chase, and the observed half-life of 21 min corresponds to about 10% of the cell doubling time. Poly(A)+-RNA was analyzed by gel electrophoresis under denaturing and nondenaturing conditions. A correlation was established between the apparent secondary structure and the turnover rate of poly(A)+-RNA species.