title: Cryptochrome 3 from Arabidopsis thaliana: structural and functional analysis of its complex with a folate light antenna.
abstract: Cryptochromes are almost ubiquitous blue-light receptors and act in several species as central components of the circadian clock. Despite being evolutionary and structurally related with DNA photolyases, a class of light-driven DNA-repair enzymes, and having similar cofactor compositions, cryptochromes lack DNA-repair activity. Cryptochrome 3 from the plant Arabidopsis thaliana belongs to the DASH-type subfamily. Its crystal structure determined at 1.9 Angstroms resolution shows cryptochrome 3 in a dimeric state with the antenna cofactor 5,10-methenyltetrahydrofolate (MTHF) bound in a distance of 15.2 Angstroms to the U-shaped FAD chromophore. Spectroscopic studies on a mutant where a residue crucial for MTHF-binding, E149, was replaced by site-directed mutagenesis demonstrate that MTHF acts in cryptochrome 3 as a functional antenna for the photoreduction of FAD.
authors.affiliation: Philipps-Universität Marburg, Department of Chemistry, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Klar
authors.forename: Richard
authors.initials: R
authors.lastname: Pokorny
authors.forename: Julia
authors.initials: J
authors.lastname: Moldt
authors.forename: Alfred
authors.initials: A
authors.lastname: Batschauer
authors.forename: Lars-Oliver
authors.initials: LO
authors.lastname: Essen
mesh_terms: D000409:Alanine; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D056931:Cryptochromes; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000737:chemistry* / Q000378:metabolism*; D004583:Electrons; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D005492:Folic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D005973:Glutamine; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D013053:Spectrophotometry; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D029681:Arabidopsis Proteins; D056931:Cryptochromes; D045342:Light-Harvesting Protein Complexes; D050505:Mutant Proteins; D005973:Glutamine; D005182:Flavin-Adenine Dinucleotide; C032418:5,11-methenyltetrahydrohomofolate; D005492:Folic Acid; C515145:Cry3 protein, Arabidopsis; D004255:Deoxyribodipyrimidine Photo-Lyase; D000409:Alanine