Isolation and Identification of the NRO1 Gene, Which is Responsible for Recognition of Fatty Acid Species in the Yeast Saccharomyces Cerevisiae

Caitlin Peirce, Hope College
Regina O'Brien, Hope College
Katherine Heneveld, Hope College
Joseph Stukey, Hope College
Virginia McDonough, Hope College

Supported by a Walker-Barr Summer Research Scholar Award from Hope College Biology Department


When dietary unsaturated fatty acids (UFAs) are present, Saccharomyces cerevisiaecells down-regulate expression of the gene OLE1, which encodes the enzyme 9 desaturase, responsible for all endogenous production of UFAs. A screen was designed to isolate mutants defective in recognition of the presence of UFAs, and subsequent transcriptional regulation of the 9-desaturase. Using a reporter gene construct controlled by the OLE1 promoter, several mutants were identified and one mutant, KH2, was chosen for additional characterization. The mutation that renders KH2 incapable of molecular response to UFAs is a recessive trait due to a single mutation, we call nro1 (no regulation of OLE1). KH2 does perform normal post-transcriptional regulation of the desaturase, indicating its effect is limited to transcriptional regulation. In order to identify the gene responsible for this phenotype, a yeast genomic library was transformed into the nro1 mutant, and plasmids that returned the mutant to wild type phenotype were chosen for further evaluation. These plasmids may contain the gene NRO1, encoding the protein responsible for the sensing of exogenous UFAs