GSBS Student Publications


An internal open reading frame triggers nonsense-mediated decay of the yeast SPT10 mRNA

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Molecular Genetics and Microbiology



Document Type


Medical Subject Headings

5' Untranslated Regions; Amino Acid Sequence; Base Sequence; Codon, Nonsense; Databases as Topic; Eukaryotic Initiation Factor-3; Fungal Proteins; Gene Expression Regulation, Fungal; Genes, Fungal; Kinetics; Molecular Sequence Data; Mutation; Open Reading Frames; Peptide Initiation Factors; Polyribosomes; Prokaryotic Initiation Factor-3; Protein Biosynthesis; RNA Helicases; RNA, Messenger; Ribosomes; Saccharomyces cerevisiae; *Saccharomyces cerevisiae Proteins; *Transcription Factors


Life Sciences | Medicine and Health Sciences


Yeast cells containing a temperature-sensitive mutation in the PRT1 gene were found to selectively stabilize mRNAs harboring early nonsense codons. The similarities between the mRNA decay phenotypes of prt1-1 cells and those lacking the nonsense-mediated mRNA decay (NMD) factor Upf1p led us to determine whether both types of mutations cause the accumulation of the same mRNAs. Differential display analysis and mRNA half-life measurements demonstrated that the HHF2 mRNA increased in abundance in prt1-1 and upf1Delta cells, but did not manifest a change in decay rate. In both mutant strains this increase was attributable to stabilization of the SPT10 transcript, an mRNA encoding a transcriptional regulator of HHF2. Analyses of chimeric mRNAs used to identify the cis-acting basis for NMD of the SPT10 mRNA indicated that ribosomes scan beyond its initiator AUG and initiate at the next downstream AUG, resulting in premature translation termination. By searching a yeast database for transcripts with sequence features similar to those of the SPT10 mRNA, other transcripts that decay by the NMD pathway were identified. Our results demonstrate that mRNAs undergoing leaky scanning are a new class of endogenous NMD substrate, and suggest the existence of a novel cellular regulatory circuit.

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Citation: EMBO J. 1999 Nov 1;18(21):6134-45. Link to article on publisher's site

DOI of Published Version


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Link to Article in PubMed

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The EMBO journal

PubMed ID