COMPREHENSIVE CLONING OF SCHIZOSACCHAROMYCES-POMBE GENES ENCODING TRANSLATION ELONGATION-FACTORS

In the course of the Schizosaccharomyces pombe cDNA project, we succee ded in cloning all the genes encoding translation elongation factors E F-1 alpha EF-1 beta, EF-1 gamma, EF-2 and EF-3. With the exception of the EF-1 gamma gene, the nucleotide (nt) sequence of S. pombe elongati on factors has not been previously reported. For EF-1 alpha, we found three genes whose amino acid (aa) sequences are quite homologous each other (99.5%), but whose 3' untranslated regions (UTRs) are completely different. Southern blot indicated that those three EF-1 alpha genes are located at different loci. Northern analysis indicated that one of three EF-IV. genes was inducible with UV-irradiation, while the level of expression for another of three EF-1 alpha genes was repressed by UV and heat-shock (HS) treatments. The aa sequence predicted from the nt sequence of the S. pombe EF-1 beta cDNA clone covered almost all th e coding sequence (CDS) of EF-1 beta except the first methionine which has 55.4% identity with that of S. cerevisiae. We also identified two copies of S. pombe EF-2 genes. Their aa sequences deduced from nt seq uences are identical (100%), but they have different 3' UTRs. The loca tion of these two EF-2 genes in different loci was proved by Southern analysis. The S. pombe EF-3 cDNA clone encoded only a third of the CDS from the C-terminal and its deduced aa sequence has a 76% identity wi th those of other yeasts and fungi.