03.03.2020
+++ News Ticker Science #32 +++ Plant Stress +++
Senescence master regulator ORE1 is a direct substrate of CPK1 in Arabidopsis.
Professor Tina Romeis, and her partners of the Collaborative Research Centre (CRC) 973 “Priming and Memory of Organismic Responses to Stress“, have discovered that the Arabidopsis senescence master regulator ORE1 is a direct substrate of the calcium-dependent protein kinase CPK1. The finding was published in The Plant Cell.
Calcium-regulated protein kinases (CPKs) are key components of intracellular signaling that mediate rapid stress-induced responses in plants. Accordingly, CPKs have been identified as crucial early signaling components that guarantee plant survival under drought conditions as well as upon pathogen attack. To find phosphorylation substrates of CPK1 in Arabidopsis thaliana, the scientists used a novel approach in which they analyzed a conditionally expressed constitutively active CPK1 variant in conjunction with in vivo phosphoproteomics. As a result, they identified Arabidopsis thaliana ORESARA1 (ORE1), the developmental master regulator of senescence, as a direct CPK1 phosphorylation substrate. Plants that overexpress ORE1, but not an ORE1 variant lacking the CPK1 phosphorylation hotspot, promote early senescence. Their data not only link CPK1 to the induction of senescence-related cell death but also show that senescence master regulator ORE1, known to be strictly controlled at the transcript level by gene regulatory networks, is subject to an additional layer of control, namely the post-translational modification of ORE1 catalyzed by CPK1.
With their approach, the scientists present a suitable method to identify kinase target proteins that exhibit low abundance, transient phosphorylation, or act in yet undescribed biological contexts.
