Tseng, Tong-Seung , Briggs, Winslow R. .
Arabidopsis Ser/Thr protein phosphatase 2A dephosphorylates PHOTOTROPIN 2 (PHOT2).
We found that the regulatory A1 subunit of protein phosphatase 2A (PP2A) interacts with PHOTOTROPIN 2 (PHOT2) in yeast and in in vitro pull-down assays. The null mutation of PP2AA1 (rcn1, ROOTS CURL IN NAPHTHYLPHTHALAMIC ACID 1) lowers the activity of PP2A to 40-60% of that of the wild type. Using a phot1-5/rcn1 double mutant, we found both earlier development of phototropic curvature and greater sensitivity at low fluence rates of the double mutant than the single phot1-5 mutant, harboring normal RCN1. We reasoned that impaired dephosphorylation of PHOT2 might result in longer activation state for the photoreceptor and the increased photosensitivity for phototropism. We found that the phosphorylation state of PHOT2 in the rcn1 mutant background was prolonged, compared to PHOT2 in the wild type RCN1 background. Preliminary experiments with the phot2-1/rcn1 double mutant showed that rcn1mutation has very little or no effect on the phototropic responses mediated by PHOT1. Also, the rcn1 mutation did not prolong the phosphorylation state of PHOT1, suggesting that the Ser/Thr PP2A activity, mediated through the interaction of PP2AA1 with PHOT2, is specifically involved in dephosphorylating PHOT2. These studies uncovered a new level of regulation of the consequences of activating PHOT2.
Log in to add this item to your schedule
1 - Carnegie Institution of Washington, Department of Plant Biology, 260 Panama street, Stanford, CA, 94305, USA
2 - Carnegie Institution of Washington, Department of Plant Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM