Abstract
The levels of four ribosomal protein (rp) mRNAs in different mutant strains were determined by hybridization of radiolabeled cloned genes to RNA fractionated on CH
3HgOH gels and transferred to DBM paper. Two ribosomal protein genes (rp 51 and rp 52) controlled by the locus
RNA2 have dramatically decreased mRNA levels after a shift-up to the nonpermissive temperature in a strain carrying the
rna2 mutation (
ts368). Two ribosomal protein genes not controlled by the
RNA2 locus and several control nonribosomal protein genes are relatively unaffected by the temperature shift in this strain. Other genes in the vicinity of one of the
rna2-sensitive ribosomal protein genes (the rp 51 gene) are insensitive to the
rna2 gene product, suggesting that all ribosomal protein genes do not occur in clusters and that the
RNA2 gene product does not affect a large region of chromatin. In
ts368 at the nonpermissive temperature, the concentration of higher molecular weight transcripts complementary to the rp 51 and the rp 52 plasmids is increased. Analysis of the rp 51 plasmid transcripts reveals that the temperature-induced higher molecular weight transcripts differ from the mature rp 51 mRNA by the presence of an intron. This observation and the kinetics with which the concentration of the various rp 51 transcripts change after a temperature shift suggest that the effect of rna2 may be at the level of processing of rp mRNA.