title: Trp triad-dependent rapid photoreduction is not required for the function of Arabidopsis CRY1.
abstract: Cryptochromes in different evolutionary lineages act as either photoreceptors or light-independent transcription repressors. The flavin cofactor of both types of cryptochromes can be photoreduced in vitro by electron transportation via three evolutionarily conserved tryptophan residues known as the "Trp triad." It was hypothesized that Trp triad-dependent photoreduction leads directly to photoexcitation of cryptochrome photoreceptors. We tested this hypothesis by analyzing mutations of Arabidopsis cryptochrome 1 (CRY1) altered in each of the three Trp-triad tryptophan residues (W324, W377, and W400). Surprisingly, in contrast to a previous report all photoreduction-deficient Trp-triad mutations of CRY1 remained physiologically and biochemically active in Arabidopsis plants. ATP did not enhance rapid photoreduction of the wild-type CRY1, nor did it rescue the defective photoreduction of the CRY1(W324A) and CRY1(W400F) mutants that are photophysiologically active in vivo. The lack of correlation between rapid flavin photoreduction or the effect of ATP on the rapid flavin photoreduction and the in vivo photophysiological activities of plant cryptochromes argues that the Trp triad-dependent photoreduction is not required for the function of cryptochromes and that further efforts are needed to elucidate the photoexcitation mechanism of cryptochrome photoreceptors.
authors.affiliation: Laboratory of Soil and Plant Molecular Genetics, College of Plant Science, Jilin University, Changchun 130062, China; Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095;
authors.forename: Jie
authors.initials: J
authors.lastname: Gao
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095; Basic Forestry and Proteomics Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China;
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Physics, Ohio State University, Columbus, OH 43210; Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Laboratory of Soil and Plant Molecular Genetics, College of Plant Science, Jilin University, Changchun 130062, China;
authors.forename: Mingdi
authors.initials: M
authors.lastname: Bian
authors.affiliation: Laboratory of Soil and Plant Molecular Genetics, College of Plant Science, Jilin University, Changchun 130062, China;
authors.forename: Weixian
authors.initials: W
authors.lastname: Deng
authors.affiliation: Laboratory of Soil and Plant Molecular Genetics, College of Plant Science, Jilin University, Changchun 130062, China;
authors.forename: Zecheng
authors.initials: Z
authors.lastname: Zuo
authors.affiliation: Laboratory of Soil and Plant Molecular Genetics, College of Plant Science, Jilin University, Changchun 130062, China; zmyang@jlu.edu.cn zhong.28@osu.edu clin@mcdb.ucla.edu.
authors.forename: Zhenming
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Physics, Ohio State University, Columbus, OH 43210; Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210 zmyang@jlu.edu.cn zhong.28@osu.edu clin@mcdb.ucla.edu.
authors.forename: Dongping
authors.initials: D
authors.lastname: Zhong
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095; zmyang@jlu.edu.cn zhong.28@osu.edu clin@mcdb.ucla.edu.
authors.forename: Chentao
authors.initials: C
authors.lastname: Lin
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D056931:Cryptochromes / Q000737:chemistry* / Q000378:metabolism*; D018546:Hypocotyl / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction / Q000528:radiation effects; D055668:Photochemical Processes / Q000528:radiation effects*; D013329:Structure-Activity Relationship; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D014364:Tryptophan; D000255:Adenosine Triphosphate
keywords: Arabidopsis; Trp-triad; blue light; cryptochrome; photoreduction