Speaker: Ullas Pedmale, assistant professor at Cold Spring Harbor Laboratory

Title: ‘Regulation of plant photoreceptors by reversible ubiquitination’

Abstract: As plants are sessile organisms, their growth environment plays a critical role in their growth and development. Light is one of the most important factors as it not only supplies the energy for photosynthesis but also provides information about the seasons and local growth environment. Light is perceived by a suite of photoreceptors, and cryptochromes (CRYs) are one such class of proteins that absorb UV-A/blue-light (BL). CRYs are vital for many processes in plants such as seedling development, circadian rhythms, and the transition to flowering. CRY2 protein accumulates in the dark and in the vegetational shade and is readily degraded by the 26S proteasome under high intensities of BL. Therefore, it is obvious that the CRY2 protein level and activity are tightly regulated by light in order to ensure proper signaling and response. However, the molecular mechanisms and proteins involved in regulating CRY2 protein levels remained unknown so far. In Arabidopsis, we have identified a novel deubiquitinase (DUB) protein which physically interacts with CRY2 protein and regulates its activity and quantity. DUBs remove covalently attached ubiquitin molecules from their substrates and reverse the effects of E3 ubiquitin ligases, thus antagonizing the activity of the proteasomal degradation. We will present genetic and biochemical data to demonstrate the role of DUB in regulating CRY2 activity in flowering and photomorphogenesis. Together, our results will provide novel insight into the regulation of CRYs by reversible ubiquitination as well as the role of DUBs in plant development which is largely unknown so far.

Host: Dior Kelley, GDCB assistant professor

Please join us for refreshments before the seminar outside Room 1414 of the Molecular Biology Building.