The gene for yeast's most abundant elongation factor stayed uncharacterized despite heavy transcription. TEF1 and TEF2 were cloned, sequenced, and identified by homology search as EF-1alpha. A TEF1 deletion strain stayed viable because TEF2 alone sustains growth.
Key findings
01
Two genes, TEF1 and TEF2, encoding the translation elongation factor EF-1α were cloned from S. cerevisiae. TEF1 mapped to chromosome II near LYS2, and a TEF1 deletion strain remained viable under aerobic and anaerobic conditions, demonstrating that TEF2 expression alone is sufficient to support cell growth. Both genes produce a 1.6-kb transcript conserved across all 21 Saccharomyces strains tested.
02
DNA sequencing of TEF1 revealed a 458-amino-acid open reading frame with ~80% similarity to the translation elongation factor EF-1α from shrimp Artemia and significant similarity to E. coli EF-Tu, identified via Dayhoff protein data bank searching. This sequence homology definitively established TEF1 as the S. cerevisiae EF-1α gene and enabled prediction of the full protein sequence from DNA data alone.
03
Southern hybridization of TEF1 probes to DNA from multiple Saccharomyces species and yeast genera revealed that gene duplication of EF-1α is common across yeast evolution, with sequence conservation markedly higher than that of genes encoding amino acid biosynthetic enzymes. This elevated conservation across genera suggests strong purifying selection on the translational machinery EF-1α function.
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