A novel protein phosphatase indirectly regulates phytochrome-interacting factor 3 via phytochrome.
Light signal transduction in plants involves an intricate series of pathways which is finely regulated by interactions between specific signalling proteins, as well as by protein modifications such as phosphorylation and ubiquitination. The identification of novel phytochrome-interacting proteins and the precise signalling mechanisms that they mediate is still ongoing. In our present study, we show that the newly identified putative phytochrome-associated protein, PAPP2C (phytochrome-associated protein phosphatase type 2C), interacts in the nucleus with phyA (phytochrome A) and phyB, both in vitro and in vivo. Moreover, the phosphatase activity of PAPP2C and its association with phytochromes were found to be enhanced by red light, indicating that it plays a role in mediating phytochrome signalling. In particular, PAPP2C specifically binds to the N-terminal PHY domain of the phytochromes. We thus speculate that this interaction reflects a unique regulatory function of this phosphatase toward established phytochrome-associated proteins. We also show that PAPP2C effectively dephosphorylates phytochromes in vitro. Interestingly, PAPP2C indirectly mediates the dephosphorylation of PIF3 (phytochrome-interacting factor 3) in vitro. Taken together, we suggest that PAPP2C functions as a regulator of PIF3 by dephosphorylating phytochromes in the nucleus.
Graduate School of Biotechnology and Plant Metabolism Research Center, Kyung Hee University, Yongin, Korea, 446-701.
Bong-Kwan
BK
Phee
Jeong-Il
JI
Kim
Dong Ho
DH
Shin
Jihye
J
Yoo
Kyoung-Jin
KJ
Park
Yun-Jeong
YJ
Han
Yong-Kook
YK
Kwon
Man-Ho
MH
Cho
Jong-Seong
JS
Jeon
Seong Hee
SH
Bhoo
Tae-Ryong
TR
Hahn
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D010641:Phenotype; D010766:Phosphorylation; D010834:Phytochrome / Q000378:metabolism*; D051942:Phytochrome A / Q000378:metabolism; D051939:Phytochrome B / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
D029681:Arabidopsis Proteins; D051942:Phytochrome A; D010834:Phytochrome; D051939:Phytochrome B