Domain Swapping to Assess the Mechanistic Basis ofArabidopsisPhototropin 1 Receptor Kinase Activation and Endocytosis by Blue Light
Open Access
- 1 October 2009
- journal article
- Published by Oxford University Press (OUP) in Plant Cell
- Vol. 21 (10), 3226-3244
- https://doi.org/10.1105/tpc.109.067876
Abstract
Phototropins (phot1 and phot2) are plasma membrane–associated receptor kinases that respond specifically to blue and UV wavelengths. In addition to a C-terminal Ser/Thr kinase domain, phototropins contain two N-terminal chromophore binding LOV domains that function as photoswitches to regulate a wide range of enzymatic activities in prokaryotes and eukaryotes. Through domain swapping, we show that the photochemical properties of Arabidopsis thaliana phot1 rely on interactions between LOV1 and LOV2, which are facilitated by their intervening linker sequence. Functional analysis of domain-swap proteins supports a mechanism whereby LOV2 acts as a dark-state repressor of phot1 activity both in vitro and in vivo. Moreover, we find a photoactive role for LOV1 in arresting chloroplast accumulation at high light intensities. Unlike LOV2, LOV1 cannot operate as a dark-state repressor, resulting in constitutive receptor autophosphorylation and accelerated internalization from the plasma membrane. Coexpression of active and inactive forms of phot1 demonstrates that autophosphorylation can occur intermolecularly, independent of LOV1, via light-dependent receptor dimerization in vivo. Indeed, transphosphorylation is sufficient to promote phot1 internalization through a clathrin-dependent endocytic pathway triggered primarily by phosphorylation of Ser-851 within the kinase activation loop. The mechanistic implications of these findings in regard to light-driven receptor activation and trafficking are discussed.Keywords
This publication has 76 references indexed in Scilit:
- A genetically encoded photoactivatable Rac controls the motility of living cellsNature, 2009
- Phytochrome A Regulates the Intracellular Distribution of Phototropin 1–Green Fluorescent Protein in Arabidopsis thalianaPlant Cell, 2008
- Plant Receptors Go Endosomal: A Moving View on Signal TransductionPlant Physiology, 2008
- Sequential Transphosphorylation of the BRI1/BAK1 Receptor Kinase Complex Impacts Early Events in Brassinosteroid SignalingDevelopmental Cell, 2008
- Blue light-induced autophosphorylation of phototropin is a primary step for signalingProceedings of the National Academy of Sciences of the United States of America, 2008
- The Plant Defense Elicitor Cryptogein Stimulates Clathrin-Mediated Endocytosis Correlated with Reactive Oxygen Species Production in Bright Yellow-2 Tobacco CellsPlant Physiology, 2008
- UV-B Promotes Rapid Nuclear Translocation of the Arabidopsis UV-B–Specific Signaling Component UVR8 and Activates Its Function in the NucleusPlant Cell, 2007
- Abscisic Acid Triggers the Endocytosis of the Arabidopsis KAT1 K+ Channel and Its Recycling to the Plasma MembraneCurrent Biology, 2007
- Clathrin-Mediated Constitutive Endocytosis of PIN Auxin Efflux Carriers in ArabidopsisCurrent Biology, 2007
- Physiological Roles of the Light, Oxygen, or Voltage Domains of Phototropin 1 and Phototropin 2 in ArabidopsisPlant Physiology, 2006