This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Yun, D. F. Articles by Sherman, F. Search for Related Content PubMed PubMed Citation Articles by Yun, D. F. Articles by Sherman, F.

 Previous Article  |  Next Article 

Mol. Cell. Biol., Feb 1995, 1021-1033, Vol 15, No. 2
Copyright © 1995, American Society for Microbiology

Initiation of translation can occur only in a restricted region of the CYC1 mRNA of Saccharomyces cerevisiae

DF Yun and F Sherman
Department of Biochemistry, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642.

The steady-state levels and half-lives of CYC1 mRNAs were estimated in a series of mutant strains of Saccharomyces cerevisiae containing (i) TAA nonsense codons, (ii) ATG initiator codons, or (iii) the sequence ATA ATG ACT TAA (denoted ATG-TAA) at various positions along the CYC1 gene, which encodes iso-1-cytochrome c. These mutational alterations were made in backgrounds lacking all internal in-frame and out-of-frame ATG triplets or containing only one ATG initiator codon at the normal position. The results revealed a "sensitive" region encompassing approximately the first half of the CYC1 mRNA, in which nonsense codons caused Upf1-dependent degradation. This result and the stability of CYC1 mRNAs lacking all ATG triplets, as well as other results, suggested that degradation occurs unless elements associated with this sensitive region are covered with 80S ribosomes, 40S ribosomal subunits, or ribonucleoprotein particle proteins. While elongation by 80S ribosomes could be prematurely terminated by TAA codons, the scanning of 40S ribosomal units could not be terminated solely by TAA codons but could be disrupted by the ATG-TAA sequence, which caused the formation and subsequent prompt release of 80S ribosomes. The ATG-TAA sequence caused degradation of the CYC1 mRNA only when it was in the region spanning nucleotide positions -27 to +37 but not in the remaining 3' distal region, suggesting that translation could initiate only in this restricted initiation region. CYC1 mRNA distribution on polyribosomes confirmed that only ATG codons within the initiation region were translated at high efficiency. This initiation region was not entirely dependent on the distance from the 5' cap site and was not obviously dependent on the short-range secondary structure but may simply reflect an open structural requirement for initiation of translation of the CYC1 mRNA.

This article has been cited by other articles:

• Kebaara, B., Nazarenus, T., Taylor, R., Forch, A., Atkin, A. L. (2003). The Upf-dependent decay of wild-type PPR1 mRNA depends on its 5'-UTR and first 92 ORF nucleotides. Nucleic Acids Res 31: 3157-3165 [Abstract] [Full Text]  
• Das, B., Guo, Z., Russo, P., Chartrand, P., Sherman, F. (2000). The Role of Nuclear Cap Binding Protein Cbc1p of Yeast in mRNA Termination and Degradation. Mol. Cell. Biol. 20: 2827-2838 [Abstract] [Full Text]  
• McCarthy, J. E. G. (1998). Posttranscriptional Control of Gene Expression in Yeast. Microbiol. Mol. Biol. Rev. 62: 1492-1553 [Abstract] [Full Text]  
• Linz, B., Koloteva, N., Vasilescu, S., McCarthy, J. E.G. (1997). Disruption of Ribosomal Scanning on the 5'-Untranslated Region, and Not Restriction of Translational Initiation per se, Modulates the Stability of Nonaberrant mRNAs in the Yeast Saccharomyces cerevisiae. J. Biol. Chem. 272: 9131-9140 [Abstract] [Full Text]