Document Detail

Mechanism of photosignaling by Drosophila cryptochrome: role of the redox status of the flavin chromophore.
MedLine Citation:
PMID:  24379403     Owner:  NLM     Status:  MEDLINE    
Cryptochrome (CRY) is the primary circadian photoreceptor in Drosophila. Upon light absorption, dCRY undergoes a conformational change that enables it to bind to Timeless (dTIM), as well as to two different E3 ligases that ubiquitylate dTIM and dCRY, respectively, resulting in their proteolysis and resetting the phase of the circadian rhythm. Purified dCRY contains oxidized flavin (FADox), which is readily photoreduced to the anionic semiquinone through a set of 3 highly conserved Trp residues (Trp triad). The crystal structure of dCRY has revealed a fourth Trp (Trp-536) as a potential electron donor. Previously, we reported that the Trp triad played no role in photoinduced proteolysis of dCRY in Drosophila cells. Here we investigated the role of the Trp triad and Trp-536, and the redox status of the flavin on light-induced proteolysis of both dCRY and dTIM and resetting of the clock. We found that both oxidized (FADox) and reduced (FAD) forms of dCRY undergo light-induced conformational change in vitro that enable dCRY to bind JET and that Trp triad and Trp-536 mutations that block known or presumed intraprotein electron transfer reactions do not affect dCRY phototransduction under bright or dim light in vivo as measured by light-induced proteolysis of dCRY and dTIM in Drosophila S2R+ cells. We conclude that both oxidized and reduced forms of dCRY are capable of photosignaling.
Nuri Ozturk; Christopher P Selby; Dongping Zhong; Aziz Sancar
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2013-12-30
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  289     ISSN:  1083-351X     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2014 Feb 
Date Detail:
Created Date:  2014-02-24     Completed Date:  2014-04-22     Revised Date:  2014-06-25    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4634-42     Citation Subset:  IM    
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MeSH Terms
Cryptochromes / chemistry,  isolation & purification,  metabolism*
Drosophila Proteins / chemistry,  isolation & purification,  metabolism*
Drosophila melanogaster / metabolism*
Eye Proteins / chemistry,  isolation & purification,  metabolism*
Flavin-Adenine Dinucleotide / metabolism
Flavins / metabolism*
Light Signal Transduction* / radiation effects
Mutant Proteins / chemistry,  isolation & purification,  metabolism
Mutation / genetics
Oxidation-Reduction / radiation effects
Protein Conformation
Proteolysis / radiation effects
Sf9 Cells
Tryptophan / genetics
Grant Support
Reg. No./Substance:
0/Cryptochromes; 0/Drosophila Proteins; 0/Eye Proteins; 0/Flavins; 0/Mutant Proteins; 0/cryptochrome protein, Drosophila; 0/timeless protein, Drosophila; 146-14-5/Flavin-Adenine Dinucleotide; 8DUH1N11BX/Tryptophan

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