Genetic selection for mutations that reduce or abolish ribosomal recognition of the HIS4 translational initiator region

Journal Article · Fri Jul 01 04:00:00 EDT 1988 · Mol. Cell. Biol.; (United States)

DOI:https://doi.org/10.1128/MCB.8.7.2955· OSTI ID:6272589

Donahue, T F; Cigan, A M

A unique genetic selection was devised at the HIS4 locus to address the mechanism of translation initiation in Saccharomyces cerevisiae and to probe sequence requirements at the normal translational initiator region that might participate in ribosomal recognition of the AUG start codon. The first AUG codon at the 5' end of the HIS4 message serves as the start site for translation, and the -3 and +4 nucleotide positions flanking this AUG (AXXAUGG) correspond to a eucaryotic consensus start region. Despite this similarity, direct selection for mutations that reduce or abolish ribosomal recognition of this region does not provide any insight into the functional nature of flanking nucleotides. The only mutations identified that affected recognition of this region were alterations in the AUG start codon. Among 150 spontaneous isolates, 26 were shown to contain mutations in the AUG start codon, including all +1 changes (CUG, GUG, and UUG), all +3 changes (AUA, AUC, and AUU), and one +2 change (ACG). These seven mutations of the AUG start codon, as well as AAG and AGG constructed in vitro, were assayed for their ability to support HIS4 expression. No codon other than AUG is physiologically relevant to translation initiation at HIS4 as determined by growth tests and quantitated in his4-lacZ fusion strains. These data and analysis of other his4 alleles are consistent with a mechanism of initiation at HIS4 as proposed in the scanning model whereby the first AUG codon nearest the 5' end of the message serves as the start site for translation and points to the AUG codon in S, cerevisiae as an important component for ribosomal recognition of the initiator region.

• Research Organization: Dept. of Molecular Biology, Northwestern Univ. Medical School, 303 East Chicago Avenue, Chicago, IL (US)
• OSTI ID: 6272589
• Journal Information: Mol. Cell. Biol.; (United States), Journal Name: Mol. Cell. Biol.; (United States) Vol. 8:7; ISSN MCEBD
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
BIOLOGICAL PATHWAYS
CELL CONSTITUENTS
CODONS
DATA
DATA ANALYSIS
DNA SEQUENCING
EUMYCOTA
EXPERIMENTAL DATA
FUNGI
GENE MUTATIONS
GENE OPERONS
GENETIC MAPPING
IN VITRO
INFORMATION
MAPPING
MICROORGANISMS
MOLECULAR BIOLOGY
MUTATIONS
NUMERICAL DATA
ORGANOIDS
PLANTS
RIBOSOMES
SACCHAROMYCES
SACCHAROMYCES CEREVISIAE
STRUCTURAL CHEMICAL ANALYSIS
YEASTS