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.

Cloning of Histidyl-tRNA Synthetase in C. elegans

Yousef G. Amaar and David L. Baillie

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.