The CRY1 blue light photoreceptor of Arabidopsis interacts with phytochrome A in vitro.
Plants have at least two major photosensory receptors: phytochrome (absorbing primarily red/far-red light) and cryptochrome (absorbing blue/UV-A light); considerable physiological and genetic evidence suggests some form of communication or functional dependence between the receptors. Here, we demonstrate in vitro, using purified recombinant photoreceptors, that Arabidopsis CRY1 and CRY2 (cryptochrome) are substrates for phosphorylation by a phytochrome A-associated kinase activity. Several mutations within the CRY1 C terminus lead to reduced phosphorylation by phytochrome preparations in vitro. Yeast two-hybrid interaction studies using expressed C-terminal fragments of CRY1 and phytochrome A from Arabidopsis confirm a direct physical interaction between both photoreceptors. In vivo labeling studies and specific mutant alleles of CRY1, which interfere with the function of phytochrome, suggest the possible relevance of these findings in vivo.
Ahmad
M
M
Department of Biology, University of Pennsylvania, Philadelphia 19104-6018, USA. mahmad@sas.upenn.edu
Jarillo
J A
JA
Smirnova
O
O
Cashmore
A R
AR
D000483:Alleles; D017360:Arabidopsis / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics / Q000502:physiology; D010710:Phosphates; D010766:Phosphorylation / Q000528:radiation effects; D010770:Phosphotransferases / Q000378:metabolism; D010786:Photoreceptor Cells / Q000737:chemistry / Q000378:metabolism*; D017956:Photoreceptor Cells, Invertebrate; D010834:Phytochrome / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D051942:Phytochrome A; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics
D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; C497973:PHYA protein, Arabidopsis; D010710:Phosphates; D051942:Phytochrome A; D010940:Plant Proteins; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; C119828:cry protein, Drosophila; D010834:Phytochrome; D010770:Phosphotransferases