Dimerization of the plant photoreceptor phototropin is probably mediated by the LOV1 domain.
Phototropin is a membrane-bound UV-A/blue light photoreceptor of plants responsible for phototropism, chloroplast migration and stomatal opening. Characteristic are two LOV domains, each binding one flavin mononucleotide, in the N-terminal half and having a serine/threonine kinase domain in the C-terminal half of the molecule. We purified the N-terminal half of oat phototropin 1, containing LOV1 and LOV2 domains, as a soluble fusion protein with the calmodulin binding peptide (CBP) by expression in Escherichia coli. Gel chromatography showed that it was dimeric in solution. While the fusion protein CBP-LOV2 was exclusively monomeric in solution, the fusion protein CBP-LOV1 occurred as monomer and dimer. The proportion of dimer increased on prolonged incubation. We conclude that native phototropin is a dimer and that the LOV1 domain is probably responsible for dimerization.
Salomon
Michael
M
Department Biologie I (Botanik), Ludwig-Maximilians-Universität München, Menzingerstr. 67, 80638 München, Germany.
Lempert
Ulrika
U
Rüdiger
Wolfhart
W
D018554:Avena / Q000378:metabolism*; D001665:Binding Sites; D001683:Biological Clocks; D003001:Cloning, Molecular; D056931:Cryptochromes; D019281:Dimerization; D005486:Flavin Mononucleotide / Q000378:metabolism; D005420:Flavoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
D056931:Cryptochromes; D005420:Flavoproteins; D010940:Plant Proteins; D011994:Recombinant Proteins; D005486:Flavin Mononucleotide; D017346:Protein Serine-Threonine Kinases