title: Ramshackle (Brwd3) promotes light-induced ubiquitylation of Drosophila Cryptochrome by DDB1-CUL4-ROC1 E3 ligase complex.
abstract: Cryptochrome (CRY) is the primary circadian photoreceptor in Drosophila. It resets the circadian clock by promoting light-induced degradation of the clock proteins Timeless and Period, as well as its own proteolysis. The E3 ligases that ubiquitylate Timeless and Period before degradation are known and it is known that Drosophila (d) CRY is degraded by the ubiquitin-proteasome system as well. To identify the E3 ligase for dCRY we screened candidates in S2 cells by RNAi. Knockdown of each of the 25 putative F-box proteins identified by bioinformatics did not attenuate the light-induced degradation of dCRY. However, knockdown of a WD40 protein, Bromodomain and WD repeat domain containing 3 (Brwd3) (CG31132/Ramshackle) caused strong attenuation of dCRY degradation following light exposure. We found that BRWD3 functions as a Damage-specific DNA binding protein 1 (DDB1)- and CULLIN (CUL)4-associated factor in a Cullin4-RING Finger E3 Ligase (CRL4) that mediates light-dependent binding of dCRY to CUL4-ROC1-DDB1-BRWD3, inducing ubiquitylation of dCRY and its light-induced degradation. Thus, this study identifies a light-activated E3 ligase complex essential for light-mediated CRY degradation in Drosophila cells.
authors.affiliation: Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA.
authors.forename: Nuri
authors.initials: N
authors.lastname: Ozturk
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: VanVickle-Chavez
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Akileswaran
authors.forename: Russell N
authors.initials: RN
authors.lastname: Van Gelder
authors.forename: Aziz
authors.initials: A
authors.lastname: Sancar
mesh_terms: D000818:Animals; D056931:Cryptochromes / Q000235:genetics / Q000378:metabolism*; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D008027:Light; D059748:Proteolysis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination / Q000502:physiology* / Q000528:radiation effects
chemical_list: C524125:BRWD3 protein, Drosophila; D056931:Cryptochromes; D044842:Cullin Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; D014157:Transcription Factors; C119828:cry protein, Drosophila; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases; C568503:CRL4(Cdt2) protein, Drosophila