Isolation and characterization of the yeast las21 mutants, which are sensitive to a local anestheticum, tetracaine

Abstract

We isolated and characterized yeast mutants whose growth is sensitive to a local anestheticum tetracaine and, at the same time, temperature sensitive. These mutants were collectively called las mutants (local anestheticum sensitive). The las21 mutants were analyzed in this study. The wild type LAS21 gene was cloned by exploiting temperature sensitivity of the las21 mutants and we found that LAS21 encodes ORF YJL062w which has not been analyzed before. Las21p is putative membrane protein belonging to the major facilitator super family containing plural membrane spanning domains. Complete elimination of the LAS21 ORF did not kill the cells but made their growth temperature sensitive. Interestingly, the complete loss of the LAS21 gene canceled the sensitivity to tetracaine. The ability of the las21 mutants to grow at a higher temperature was recovered in the various media containing an osmotic stabilizer or salts. Furthermore, temperature sensitivity of the las21 mutants was partially suppressed by introduction of PKC1, encoding protein kinase C, on a high copy vector. We found some genetic interactions between LAS21 and Ras/cAMP cascade genes. These results suggest that LAS21 defines unknown pathway regulating the stress response of yeast.