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Title: Crystal Structure of the Redox-Active Cofactor Dibromothymoquinone Bound to Circadian Clock Protein KaiA and Structural Basis for Dibromothymoquinone's Ability to Prevent Stimulation of KaiC Phosphorylation by KaiA

KaiA protein that stimulates KaiC phosphorylation in the cyanobacterial circadian clock was recently shown to be destabilized by dibromothymoquinone (DBMIB), thus revealing KaiA as a sensor of the plastoquinone (PQ) redox state and suggesting an indirect control of the clock by light through PQ redox changes. Here we show using X-ray crystallography that several DBMIBs are bound to KaiA dimer. Some binding modes are consistent with oligomerization of N-terminal KaiA pseudoreceiver domains and/or reduced interdomain flexibility. DBMIB bound to the C-terminal KaiA (C-KaiA) domain and limited stimulation of KaiC kinase activity by C-KaiA in the presence of DBMIB demonstrate that the cofactor may weakly inhibit KaiA-KaiC binding.
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  1. Vanderbilt-MED
Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemistry; Journal Volume: 51; Journal Issue: (41) ; 10, 2012
American Chemical Society (ACS)
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Sponsoring Org:
Country of Publication:
United States