A 5.3-kbp fragment of the KHS gene was cloned from a genomic bank of Saccharomyces cerevisiae No. 115 constructed with an E. coli as the host and YEp13 as the vector. A non-killer yeast strain was transformed to a killer strain with the multi-copy vector containing the KHS gene, and the transformant could secrete 3-4 times more killer toxin into culture media than the donor, strain No. 115. The KHS toxin was purified 80-fold from the culture filtrate by gel filtration and column chromatography. The nucleotide sequence of a 2.8-kbp fragment of the KHS DNA that was enough for the expression of the killer activity was identified, and we found an open reading frame consisted of 2124 bp. Comparison of the open reading frame and N-terminal amino acid sequence of purified KHS toxin, suggested that the presumed peptide from the KHS gene might be processed between 36Gln and 37Ala before secretion.
A strain of the yeast Saccharomyces cerevisiae coding for KHR on the chromosome secreted a toxin that kills sensitive yeasts. The transformants of multicopy vectors carrying the KHR gene could secrete 3-4-fold the killer toxin of the donor strain. This toxic substance was purified 80-fold in specific activity from the culture filtrate by gel filtration and hydrophobic column chromatography. The purified toxin gave a single protein band with molecular mass of 20 kDa on SDS-PAGE and had an isoelectric point of pH 5.3. The toxin had novel killer activity against Candida glabrata and S. cerevisiae, but did not affect bacteria, fungi, or other yeasts.
A strain of the yeast Saccharomyces cerevisiae coding for KHR on the chromosome secreted a toxin that kills sensitive yeasts. The transformants of multicopy vectors carrying the KHR gene could secrete 3-4-fold the killer toxin of the donor strain. This toxic substance was purified 80-fold in specific activity from the culture filtrate by gel filtration and hydrophobic column chromatography. The purified toxin gave a single protein band with molecular mass of 20 kDa on SDS-PAGE and had an isoelectric point of pH 5.3. The toxin had novel killer activity against Candida glabrata and S. cerevisiae, but did not affect bacteria, fungi, or other yeasts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.