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Title
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Cryptochrome 3 from Arabidopsis thaliana: structural and functional analysis of its complex with a folate light antenna.
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Authors
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T.Klar,
R.Pokorny,
J.Moldt,
A.Batschauer,
L.O.Essen.
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Ref.
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J Mol Biol, 2007,
366,
954-964.
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PubMed id
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Abstract
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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.
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