Differential expression of soybean SLTI100 gene encoding translation elongation factor 1A by abiotic stresses

The translation elongation factor 1A, eEF1A, catalyzes the binding of aminoacyl-tRNA to the A-site of the ribosome by a GTP-dependent mechanism. By subtractive suppression hybridization technique, we have isolated a soybean low-temperature inducible gene, SLTI100 encoding translation elongation factor 1A. Multiple sequence align-ments and phylogenic analysis showed that SLTI100 and other eEF1As originated from diverse organisms are highly conserved. RNA expression of SLTI100 was specifically induced by low temperature, high salt, ABA, or drought stress. Based on the subcellular localization of the corre-sponding gene product fused to GFP, we were able to con-firm that SLTI100-GFP was restricted to the nucleus and cytoplasm. We propose that soybean eEF1A may play an important role in translational regulation during abiotic stress responses in plants. Introduction In the translational elongation process, eukaryote transla-tional elongation factor 1 (eEF1) is a protein synthesis factor composed of four subunits: A, B α, Bβ and Bγ (Browing et al. 1990). Subunit eEF1A, also known as EF1α, binds ami-noacyl-tRNAs to the acceptor (A) site of the ribosome during the peptide chain elongation phase of protein syn-thesis. eEF1A (49,174 kDa) is an abundant protein repre-senting upto 5% of the soluble protein in wheat germ extracts (Browing et al. 1990) and is highly conserved in evolution (77% conservation of wheat EF1A with human EF1A) (Metz et al. 1992). In higher eukaryotes, eEF1A is typically encoded by a multigene family: in man there are 18 genes (Lund et al. 1996) while in