CLONING AND MANIPULATION OF THE SCHIZOSACCHAROMYCES-POMBE HIS7-GENETIC STUDIES( GENE AS A NEW SELECTABLE MARKER FOR MOLECULAR)

We have cloned the his7+ gene of the fission yeast Schizosaccharomyces pombe by complementation of the recessive mutant allele his7-366. The his7+ gene is able to complement a mutation of the Escherichia coli h isI gene, suggesting that his7+ encodes a phosphoribosyl-AMP cyclohydr ase. Subcloning experiments localize the gene to a 1.9-kb XbaI-BglII f ragment. We describe the construction of plasmids to facilitate the us e of his7+ as a selectable marker in S. pombe studies. Plasmid pEA2 ca rries his7+ cloned into the pUC18 polylinker. From either pEA2 or the original his7+ clone, pMN1, fragments carrying his7+ can be isolated u sing a variety of restriction enzymes for the construction of gene dis ruptions. Plasmid pEA500 is a cloning vector that carries his7+ and ar s1, yet retains the ability to use the blue/white color screen to iden tify recombinants.