Poster: Protein modification

Abs # 810: SA-inducible CK2-like activity phosphorylates TGA/OBF in Arabidopsis

Presenter:	Kang, Hong-Gu , hgk3@cornell.edu
Authors	Kang, Hong-Gu  (A)   Klessig, Daniel F (A)
Affiliations:	(A): Boyce Thompson Institute for Plant Research at Cornell University

TGA/OBF proteins are a group of bZIP transcription factor, some of which have been shown to interact with NPR1, a key regulator of systemic acquired resistance. In the present study we have investigated whether TGA activity is regulated via phosphorylation. We found that some TGA proteins are phosphorylated both in vitro and in vivo by a CK2-like activity. TGA2 was chosen for the further analysis. This phosphorylation activity can also be induced by salicylic acid (SA), an important signal molecule for plant disease resistance. Induction of the TGA2 phosphorylation by SA suggests that this event may have a regulatory function in determining its interaction with NPR1 and/or other downstream signaling components. The phosphorylation sites on TGA2 were mapped and then replaced with amino acids that either prevented phosphorylation of TGA2 or mimicked a constitutive phosphorylated amino acid. We further characterized the phosphorylation control of TGA2 using transgenic Arabidopsis expressing the altered TGA2 proteins.