Expression and structure of an elongation factor-1 alpha gene (MeEF1) fromcassava (Manihot esculenta Crantz)

In order to isolate an elongation factor-1 alpha (EF-1 alpha) gene from cas sava, a lambda EMBL3 genomic library, made from a single cassava genotype ( MBRA 534, from the CIAT cassava germplasm collection), was screened with a full length EF-1 alpha cDNA clone (blt63) from barley. Six positive clones were isolated from an amplified library and 4866 bp from one clone (MeEF1) were subcloned into pGEM3zf(-) and pGEM5zf(-). The sequence has 2709 bp 5' of the translation start site, 1347 bp of coding sequence split into two ex ons by an intron (374 bp) and 435 bp 3' of the stop codon. A 657 bp intron was also found 5' of the translation start site. The coding sequence is ver y similar, with 86% DNA sequence identity and 95% deduced amino acid sequen ce identity, to an EF-1 alpha gene from Arabidopsis thaliana. The promoter region of MeEF1 contains 3 putative control elements that are located upstr eam of the transcription start site. These control elements include a TEF1 box, a TELO box and two TATA boxes. The gene is expressed in early stages o f development and in young tissue. Transient expression using particle bomb ardment shows that the promoter drives uidA gene expression in leaves of ca ssava and Arabidopsis. An interesting feature of the MeEF1 gene is that the presence of the 5'UTR intron affects the level of expression.