Cloning and characterization of the gene coding for cytoplasmic seryl-tRNA synthetase fromSaccharomyces cerevisiae

Abstract
We have screened a Saccharomyces cerevisiae expression library with antibodies against seryl-tRNA synthetase (SerRS) from baker's yeast. In this way we obtained clones which contain serS, the structural gene for seryl-tRNA synthetase. Genomic Southern blots show that the serS gene resides on a 5.0 kb Sail fragment. Nucleotide sequence analysis of the genes revealed a single open reading frame from which we deduced the amino add sequence of the enzyme consistent with that of two peptides Isolated from SerRS. The enzyme 1s comprised of 462 amino adds consistent with earlier determinations of Us molecular weight. The codon usage of serS 1s typical of abundant yeast proteins. Nuclease SI analysis of serS mRNA defined the RNA Initiation site 20-40 bases downstream from an AT rich sequence containing the TATA box and 21–39 nucleo-tides upstream of the translation Initiation codon. Yeast strains transformed with the cloned gene overproduce seryl-tRNA synthetase U± vivo