Expression of Escherichia coli recA and ada genes in Saccharomyces cerevisiae using a vector with geneticin resistance.

Construction of E. coli-yeast shuttle plasmids containing the neo selection gene is described. The protein-coding regions of the E. coli ada or recA genes under the control of the ADH1 promoter and terminator were ligated into the SphI unique site of pNF2 to produce pMSada and pMSrecA, respectively. The plasmids were used for transformation of the haploid and diploid pso4-1 strains of S. cerevisiae and their corresponding wild types. Transformants were obtained by selection for geneticin (G418) resistance. Crude protein samples were extracted from the individual transformants. Both the RecA and Ada proteins were present in all strains containing the recA and ada genes on plasmids, respectively. Thus the geneticin selection system was successfully used for the preparation of model yeast strains.