title: Mapping the translation initiation landscape of an S. cerevisiae gene using fluorescent proteins.
abstract: Accurate and efficient gene expression requires that protein translation initiates from mRNA transcripts with high fidelity. At the same time, indiscriminate initiation of translation from multiple ATG start-sites per transcript has been demonstrated, raising fundamental questions regarding the rate and rationale governing alternative translation initiation. We devised a sensitive fluorescent reporter assay for monitoring alternative translation initiation. To demonstrate it, we map the translation initiation landscape of a Saccharomyces cerevisiae gene (RMD1) with a typical ATG sequence context profile. We found that up to 3%-5% of translation initiation events occur from alternative out-of-frame start codons downstream of the main ATG. Initiation from these codons follows the ribosome scanning model: initiation rates from different start sites are determined by ATG order, rather than their context strength. Genomic analysis of S. cerevisiae further supports the scanning model: ATG codons downstream rather than upstream of the main ATG tend to have higher context scores.
authors.affiliation: Computer Science & Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel; Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Tuval
authors.initials: T
authors.lastname: Ben-Yehezkel
authors.forename: Hadas
authors.initials: H
authors.lastname: Zur
authors.forename: Tzipy
authors.initials: T
authors.lastname: Marx
authors.forename: Ehud
authors.initials: E
authors.lastname: Shapiro
authors.forename: Tamir
authors.initials: T
authors.lastname: Tuller
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D018387:Codon, Initiator; D018965:Frameshifting, Ribosomal; D005800:Genes, Fungal; D010442:Peptide Chain Initiation, Translational; D014176:Protein Biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D018387:Codon, Initiator; D029701:Saccharomyces cerevisiae Proteins
keywords: 5′UTR; Genomics; Out-of-frame codons; S. cerevisiae; Scanning model; Translation