title: Photoconversion and nuclear trafficking cycles determine phytochrome A's response profile to far-red light.
abstract: Phytochrome A (phyA) is the only photoreceptor in plants, initiating responses in far-red light and, as such, essential for survival in canopy shade. Although the absorption and the ratio of active versus total phyA are maximal in red light, far-red light is the most efficient trigger of phyA-dependent responses. Using a joint experimental-theoretical approach, we unravel the mechanism underlying this shift of the phyA action peak from red to far-red light and show that it relies on specific molecular interactions rather than on intrinsic changes to phyA's spectral properties. According to our model, the dissociation rate of the phyA-FHY1/FHL nuclear import complex is a principle determinant of the phyA action peak. The findings suggest how higher plants acquired the ability to sense far-red light from an ancestral photoreceptor tuned to respond to red light.
authors: Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany.
authors: Julia
authors: J
authors: Rausenberger
authors: Anke
authors: A
authors: Tscheuschler
authors: Wiebke
authors: W
authors: Nordmeier
authors: Florian
authors: F
authors: Wüst
authors: Jens
authors: J
authors: Timmer
authors: Eberhard
authors: E
authors: Schäfer
authors: Christian
authors: C
authors: Fleck
authors: Andreas
authors: A
authors: Hiltbrunner
mesh_terms: D021581:Active Transport, Cell Nucleus; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D008027:Light; D008954:Models, Biological; D051942:Phytochrome A / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C497973:PHYA protein, Arabidopsis; D051942:Phytochrome A