Cryptochrome-Timeless structure reveals circadian clock timing mechanisms

© 2023. The Author(s), under exclusive licence to Springer Nature Limited..

Circadian rhythms influence many behaviours and diseases1,2. They arise from oscillations in gene expression caused by repressor proteins that directly inhibit transcription of their own genes. The fly circadian clock offers a valuable model for studying these processes, wherein Timeless (Tim) plays a critical role in mediating nuclear entry of the transcriptional repressor Period (Per) and the photoreceptor Cryptochrome (Cry) entrains the clock by triggering Tim degradation in light2,3. Here, through cryogenic electron microscopy of the Cry-Tim complex, we show how a light-sensing cryptochrome recognizes its target. Cry engages a continuous core of amino-terminal Tim armadillo repeats, resembling how photolyases recognize damaged DNA, and binds a C-terminal Tim helix, reminiscent of the interactions between light-insensitive cryptochromes and their partners in mammals. The structure highlights how the Cry flavin cofactor undergoes conformational changes that couple to large-scale rearrangements at the molecular interface, and how a phosphorylated segment in Tim may impact clock period by regulating the binding of Importin-α and the nuclear import of Tim-Per4,5. Moreover, the structure reveals that the N terminus of Tim inserts into the restructured Cry pocket to replace the autoinhibitory C-terminal tail released by light, thereby providing a possible explanation for how the long-short Tim polymorphism adapts flies to different climates6,7.

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:617

Enthalten in:

Nature - 617(2023), 7959 vom: 01. Mai, Seite 194-199

Sprache:

Englisch

Beteiligte Personen:

Lin, Changfan [VerfasserIn]
Feng, Shi [VerfasserIn]
DeOliveira, Cristina C [VerfasserIn]
Crane, Brian R [VerfasserIn]

Links:

Volltext

Themen:

Alpha Karyopherins
Cry protein, Drosophila
Cryptochromes
Drosophila Proteins
Journal Article
PER protein, Drosophila
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Tim protein, Drosophila

Anmerkungen:

Date Completed 17.05.2023

Date Revised 26.04.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1038/s41586-023-06009-4

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM356045277