Use of an oligonucleotide probe to detect transplacement of an amber mutation into a yeast histone H3 gene.

We have used a synthetic 17-mer to direct mutagenesis of the cloned yeast histone H3 gene HHT2, creating an amber mutation at amino acid 41. This point mutation did not alter the restriction pattern of the HHT2 gene nor was it expected to provide an easily scorable phenotype in vivo. Therefore, nucleic acid hybridization was used to detect this point mutation during strain construction. The oligonucleotide was used to probe yeast genomic Southern blots to detect integration of the plasmid bearing the mutant HHT2 gene into the genome, and then to score the eventual excision of the plasmid vector with retention of the mutant gene on the chromosome. This technique can be used to score virtually any engineered point mutations in yeast.