THE RIBOSOMAL-PROTEIN GENE RPS3 IS AN ESSENTIAL SINGLE-COPY GENE OF THE YEAST SACCHAROMYCES-CEREVISIAE

This communication reports the cloning, sequencing, and analysis of th e RPS3 gene from yeast, which codes for the ribosomal protein YS3. Seq uence analyses of a 2.45 kb DNA fragment revealed an open reading fram e with the potential to code for a 240 amino-acid long protein. The fi rst 20 amino acids display a 90% identity to a 20 amino-acid long prot ein sequence of yeast ribosomal protein S3, that was obtained by prote in sequencing of purified yeast ribosomal proteins. The promoter regio n of the RPS3 gene contains several upstream conserved sequence elemen ts (UAS(rpg), T-rich region) that usually regulate transcription of ri bosomal protein genes. Northern blot experiments demonstrate that this ORF is transcribed into an approximately 900 nt long mRNA. The major start site of transcription is located near position -20. The RPS3 gen e is a single copy gene in yeast. Its disruption yields non viable hap loid spores of Saccharomyces cerevisiae. (C) 1996 Academic Press, Inc.