Abstract
Proteasome-mediated protein degradation pathway is implicated in all kinds biological responses in eukaryotes. In mammals and Drosophila, proteasome pathway is shown to play important role at the core of circadian clock. It is also known that the pathway is involved in plant circadian clock processes. However, the underlying molecular mechanisms of these processes in plants are still poorly understood. In this study, we show that an F-box protein ZEITLUPE (ZTL) plays a role in targeting PSEUDO-RESPONSE REGULATOR 5 (PRR5) to proteasome-dependent degradation in Arabidopsis thaliana. Characterization of PRR5 protein levels and stability in WT, ztl mutants and ZTL-overexpression plants in various circadian conditions demonstrate that ZTL is required for proper degradation of PRR5. We also provide evidence for genetic and physical interaction of ZTL with PRR5.
