Worm Breeder's Gazette 11(4): 17
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We have serendipitously recovered a 420 base pair EcoRI cDNA fragment from a C. elegans cDNA library (obtained from B. Barstead and B. Waterston) which probably encodes a portion of the C. elegans histidyl-tRNA synthetase. This fragment was sequenced; and a 250 nucleotide sequence of this fragment was translated and the predicted peptide was used to search EMBL 22 and SWISS-PROT 13 data banks, a significant match with histidyl-tRNA synthetase is found. Our peptide sequence when compared with human histidyl-tRNA synthetase showed a 50% amino acid identity and a 85% similarity when conserved changes are taken into consideration. The 420 bp cDNA fragment was used as a probe to screen the C. elegans cDNA library to obtain a larger cDNA fragment. This resulted in the recovery of a 1.4 kb cDNA fragment that could represent the entire coding region. Both the E. coli and human histidyl-tRNA synthetase coding regions are composed of 424 and 503 codons, respectively (1,2). Using the 420 basepair cDNA fragment as a probe, a YAC filter provided by B. Waterston was used to map this gene. It is found to fall between mec-3 and lin-3 within the deficiency sDf2 on LGIV. We assume that null mutations in this gene will be lethal. The region in which the gene maps is thought to be 70% saturated for essential gene mutations (3). Thus, it is very likely that we already possess mutations in this gene. The gene lies within a 5.5 kb EcoRI genomic DNA fragment, and the gene is likely present in a single copy. We will attempt to identify the lethal which corresponds to this gene by using germ line transformation with the appropriate cosmid.