Date of this Version
Published in Gene 119:1 (September 21, 1992), pp. 57–63
The purpose of this work was to examine the tRNATrp-encoding genes (tRNATrp) of Saccharomyces cerevisiae to gain insight as to why tRNATrp amber suppressors, isolated by conventional genetic techniques, have not been reported. The results herein indicate that the haploid yeast genome contains six tRNATrp genes which map to five or six chromosomes. Not only do the six genes have identical coding sequences but their introns are also identical. Gene replacement experiments indicate that five copies of tRNATrp are sufficient for cell viability. Thus, mutation of one tRNATrp gene to a suppressor in vivo, lowering the functional number of tRNATrp genes, would not be expected to be lethal.