Unraveling moonlighting functions with yeasts.

This review considers the use of yeasts to study protein moonlighting functions. The cases discussed highlight the possibilities offered by the well-developed yeast genetics for the study of moonlighting mechanisms. The possibility to generate sets of mutants encoding different protein variants has allowed in some cases to map the regions that participate in the moonlighting function. We discuss cases of enzymes that moonlight in such different activities as control of transcription, assembly of multimeric proteins, stabilization of mitochondrial DNA or biosynthesis of CoA. The moonlighting role of an enzyme and its metabolic function seems to have evolved independently as indicated by the finding that a protein may moonlight in a yeast species but not in others. Yeasts may open ways to study possible evolutionary relationships among moonlighting proteins.