A New Mutation in Saccharomyces Cerevisiae, a Eukaryotic Yeast, Causes

Short Answer

A new mutation in Saccharomyces cerevisiae, a eukaryotic yeast, causes the cells to be unable to produce the amino acid histidine. Specifically, they cannot catalyze the first reaction in the histidine biosynthesis pathway. When examined closely, they are producing a completely wild-type enzyme for this reaction but at greatly reduced levels. Explain the mutation.