PER PROTEIN INTERACTIONS AND TEMPERATURE COMPENSATION OF A CIRCADIAN CLOCK IN DROSOPHILA

The periods of circadian clocks are relatively temperature-insensitive . Indeed, the per(L) mutation in the Drosophila melanogaster period ge ne, a central component of the clock, affects temperature compensation as well as period length. The per protein (PER) contains a dimerizati on domain (PAS) within which the per(L) mutation is located. Amino aci d substitutions at the per(L) position rendered PER dimerization tempe rature-sensitive. In addition, another region of PER interacted with P AS, and the per(L) mutation enhanced this putative intramolecular inte raction, which may compete with PAS-PAS intermolecular interactions. T herefore, temperature compensation of circadian period in Drosophila m ay be due in part to temperature-independent PER activity, which is ba sed on competition between inter- and intramolecular interactions with similar temperature coefficients.