Poster: Photomorphogenesis

Abs # 513: Arabidopsis cryptochrome2 associates with chromatin

Presenter:	Santiago-Ong, May , maysong@ucla.edu
Authors	Santiago-Ong, May  (A)   Guzman, Mayra  (A)   Shalitin, Dror  (A)   Yu, Xuhong  (A)   Lin, Chentao  (A)
Affiliations:	(A): University of California, Los Angeles

The blue light receptor cryptochrome (cry) is a protein evolved from the DNA repair enzyme photolyase and in plants, it regulates a range of processes including greening and flowering. The structural features of photolyases, including those for DNA-binding, have been conserved in cryptochromes. We used chromatin immunoprecipitations to show that Arabidopsis cry2, like photolyase, can associate with chromatin. This association with chromatin is regulated by blue light. It has previously been shown that dark-grown seedlings accumulate cry2 protein; exposure to blue light causes a decrease in cry2 levels. In contrast to this pattern of protein levels, cry2 association with chromatin increases after light exposure. Using coimmunoprecipitations, we also show that cry2 interacts with other DNA-binding proteins. We propose that cry2 association with chromatin functions to regulate transcription. Physiological responses that cryptochromes affect in blue light overlap with many of those that phytochromes, the family of red light receptors, regulate in red light. The significance of our results will be discussed in relation to the role that phytochromes play in regulating gene expression.