title: Flavin Adenine Dinucleotide and N5,N10-Methenyltetrahydrofolate are the in planta Cofactors of Arabidopsis thaliana Cryptochrome 3.
abstract: Members of the cryptochrome/photolyase family (CPF) of proteins utilize noncovalently bound light-absorbing cofactors for their biological function. Usually, the identity of these cofactors is determined after expression in heterologous systems leaving the question unanswered whether these cofactors are identical to the indigenous ones. Here, cryptochrome 3 from Arabidopsis thaliana was expressed as a fusion with the green fluorescent protein in Arabidopsis plants. Besides the confirmation of the earlier report of its localization in chloroplasts, our data indicate that fractions of the fusion protein are present in the stroma and associated with thylakoids, respectively. Furthermore, it is shown that the fusion protein expressed in planta contains the same cofactors as the His6-tagged protein expressed in Escherichia coli, that is, flavin adenine dinucleotide and N5,N10-methenyltetrahydrofolate. This demonstrates that the heterologously expressed cryptochrome 3, characterized in a number of previous studies, is a valid surrogate of the corresponding protein expressed in plants. To our knowledge, this is also a first conclusive analysis of cofactors bound to an Arabidopsis protein belonging to the CPF and purified from plant tissue.
authors.affiliation: Department of Plant Physiology and Photobiology, Faculty of Biology, Philipps-University, Marburg, Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Göbel
authors.affiliation: Department of Plant Physiology and Photobiology, Faculty of Biology, Philipps-University, Marburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Reisbacher
authors.affiliation: Department of Plant Physiology and Photobiology, Faculty of Biology, Philipps-University, Marburg, Germany.
authors.forename: Alfred
authors.initials: A
authors.lastname: Batschauer
authors.affiliation: Department of Plant Physiology and Photobiology, Faculty of Biology, Philipps-University, Marburg, Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Pokorny
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D056148:Chromatography, Reverse-Phase; D056931:Cryptochromes / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D047468:Immunoprecipitation; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013763:Tetrahydrofolates / Q000378:metabolism*
chemical_list: D056931:Cryptochromes; D011993:Recombinant Fusion Proteins; D013763:Tetrahydrofolates; D005182:Flavin-Adenine Dinucleotide; D049452:Green Fluorescent Proteins; C018092:5,10-methenyltetrahydrofolate