Rapid mapping of antigenic coding regions and constructing insertion mutations in yeast genes by mini-Tn10 "transplason" mutagenesis.

A "transplason" mutagenesis procedure was developed for the dual purposes of low resolution mapping of antigenic coding regions (using transposons) and constructing insertion mutations in yeast genes (by transplacement). Mini-Tn10 transposon derivatives containing both Escherichia coli and yeast selectable markers have been constructed. These elements are used to mutagenize lambda gt11 clones that express foreign antigens in E. coli. The transposition events are first selected in E. coli, and the effect of these insertions on antigen expression is used to locate the antigenic coding regions on the cloned DNA. Insertion mutations located within a desired yeast sequence are then substituted for the genomic copies by one-step gene transplacement. This provides a powerful method for rapidly mapping antigenic coding sequences of cloned genes and inactivating these genes in yeast to help determine their function. Several examples using this technique are presented.