CLONING AND SEQUENCING OF CDNA-ENCODING THE RICE METHIONYL-TRANSFER-RNA SYNTHETASE

Three overlapping clones of cDNA, Mos43, Mos28 and Mos60, coding for m ethionyl-tRNA synthetase were obtained by screening the Oryza sativa l ambda gt11 library. Their nucleotide sequence of 2850 bp was determine d, The deduced amino-acid sequence of the isolated clones contains a H LGN and KFSKS motifs, which are conserved for this family of enzymes a nd have been proposed to be the signature sequences for class I aminoa cyl-tRNA synthetases. A comparison of the rice MetRS primary structure with those deposited in EMBL/GenBank points to its high homology to y east, human and Caenorhabditis elegans MetRSs. Interestingly, a great similarity of its C terminus to endothelial-monocyte-activating polype ptide II (EMAPII) and yeast protein G4p1 was observed.