Abstract

Mammalian circadian clocks are driven by a transcription/translation feedback loop composed of positive regulators (CLOCK/BMAL1) and repressors (CRYPTOCHROME 1/2 (CRY1/2) and PER1/2). To understand the structural principles of regulation, we used evolutionary sequence analysis to identify co-evolving residues within the CRY/PHL protein family. Here we report the identification of an ancestral secondary cofactor-binding pocket as an interface in repressive CRYs, mediating regulation through direct interaction with CLOCK and BMAL1. Mutations weakening binding between CLOCK/BMAL1 and CRY1 lead to acceleration of the clock, suggesting that subtle sequence divergences at this site can modulate clock function. Divergence between CRY1 and CRY2 at this site results in distinct periodic output. Weaker interactions between CRY2 and CLOCK/BMAL1 at this pocket are strengthened by co-expression of PER2, suggesting that PER expression limits the length of the repressive phase in CRY2-driven rhythms. Overall, this work provides a model for the mechanism and evolutionary variation of clock regulatory mechanisms.

Details

Title
An evolutionary hotspot defines functional differences between CRYPTOCHROMES
Author
Clark Rosensweig 1 ; Reynolds, Kimberly A 2 ; Gao, Peng 3 ; Laothamatas, Isara 3 ; Shan, Yongli 3 ; Ranganathan, Rama 4 ; Takahashi, Joseph S 5   VIAFID ORCID Logo  ; Green, Carla B 3 

1  Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Neurobiology, Northwestern University, Evanston, IL, USA 
2  Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA; The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA 
3  Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA 
4  Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA; The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA; The Center for the Physics of Evolving Systems, Biochemistry and Molecular Biology, The Institute for Molecular Engineering, University of Chicago, Chicago, IL, USA 
5  Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA 
Pages
1-15
Publication year
2018
Publication date
Mar 2018
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1038/s41467-018-03503-6
ProQuest document ID
2015393519
Copyright
© 2018. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.