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Cryptochromes are blue-light photoreceptors sharing sequence similarity to photolyases, a class of flavoenzymes catalyzing repair ofUV-damagedDNAvia electron transfer mechanisms. Despite significant amino acid sequence simi-larity in both catalytic and cofactor-binding domains, cryptochromes lack DNA repair functions associated with photolyases, and the molecular mechanism involved in cryptochrome signaling remains obscure. | Eur. J. Biochem. 270 2921-2928 2003 FEBS 2003 doi 10.1046 j.1432-1033.2003.03691.x PRIORITY PAPER Novel ATP-binding and autophosphorylation activity associated with Arabidopsis and human cryptochrome-1 Jean-Pierre Bouly1 Baldissera Giovani1 2 Armin Djamei3 Markus Mueller3 Anke Zeugner1 Elizabeth A. Dudkin4 Alfred Batschauer3 and Margaret Ahmad1 4 1Universite Paris VI Paris France 2Service de Bioénérgétique Commissariat a I Energie Atomique Saclay Gif-sur-Yvette France 3Plant Physiology Phillips-Universitaet Marburg Germany 4Penn State University Media PA USA Cryptochromes are blue-light photoreceptors sharing sequence similarity to photolyases a class of flavoenzymes catalyzing repair of UV-damaged DNA via electron transfer mechanisms. Despite significant amino acid sequence similarity in both catalytic and cofactor-binding domains cryptochromes lack DNA repair functions associated with photolyases and the molecular mechanism involved in cryptochrome signaling remains obscure. Here we report a novel ATP binding and autophosphorylation activity associated with Arabidopsis cry1 protein purified from a baculo-virus expression system. Autophosphorylation occurs on serine residue s and is absent in preparations of cryptochrome depleted in flavin and or misfolded. Autophosphorylation is stimulated by light in vitro and oxidizing agents that act as flavin antagonists prevent this stimulation. Human cry1 expressed in baculovirus likewise shows ATP binding and autophosphorylation activity suggesting this novel enzymatic activity may be important to the mechanism of action of both plant and animal cryptochromes. Keywords cryptochrome photolyase blue light photoreceptor autophosphorylation. Cryptochromes are blue-light photoreceptors found in plants and animals implicated in multiple blue-light dependent signaling pathways 1 . These include de-etiolation responses such as inhibition of hypocotyl elongation and anthocyanin accumulation in plants leaf and cotyledon expansion .
