Phytochrome-specific type 5 phosphatase controls light signal flux by enhancing phytochrome stability and affinity for a signal transducer.
Environmental light information such as quality, intensity, and duration in red (approximately 660 nm) and far-red (approximately 730 nm) wavelengths is perceived by phytochrome photoreceptors in plants, critically influencing almost all developmental strategies from germination to flowering. Phytochromes interconvert between red light-absorbing Pr and biologically functional far-red light-absorbing Pfr forms. To ensure optimal photoresponses in plants, the flux of light signal from Pfr-phytochromes should be tightly controlled. Phytochromes are phosphorylated at specific serine residues. We found that a type 5 protein phosphatase (PAPP5) specifically dephosphorylates biologically active Pfr-phytochromes and enhances phytochrome-mediated photoresponses. Depending on the specific serine residues dephosphorylated by PAPP5, phytochrome stability and affinity for a downstream signal transducer, NDPK2, were enhanced. Thus, phytochrome photoreceptors have developed an elaborate biochemical tuning mechanism for modulating the flux of light signal, employing variable phosphorylation states controlled by phosphorylation and PAPP5-mediated dephosphorylation as a mean to control phytochrome stability and affinity for downstream transducers.
Ryu
Jong Sang
JS
Division of Molecular and Life Sciences and Systems Bio-Dynamics Research Center, Pohang University of Science and Technology, Hyoja-dong, Pohang, Kyungbuk, 790-784, Republic of Korea.
Kim
Jeong-Il
JI
Kunkel
Tim
T
Kim
Byung Chul
BC
Cho
Dae Shik
DS
Hong
Sung Hyun
SH
Kim
Seong-Hee
SH
Fernández
Aurora Piñas
AP
Kim
Yumi
Y
Alonso
Jose M
JM
Ecker
Joseph R
JR
Nagy
Ferenc
F
Lim
Pyung Ok
PO
Song
Pill-Soon
PS
Schäfer
Eberhard
E
Nam
Hong Gil
HG
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018554:Avena; D001665:Binding Sites / Q000502:physiology; D008027:Light; D009701:Nucleoside-Diphosphate Kinase / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D010775:Photic Stimulation; D010788:Photosynthesis / Q000502:physiology* / Q000528:radiation effects; D010834:Phytochrome / Q000378:metabolism* / Q000528:radiation effects; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary / Q000502:physiology; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology* / Q000528:radiation effects; D015854:Up-Regulation / Q000502:physiology
D029681:Arabidopsis Proteins; D010834:Phytochrome; D012694:Serine; C121988:nucleoside diphosphate kinase 2; D009701:Nucleoside-Diphosphate Kinase; C498049:PAPP5 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases