4g86

Crystal structure of the redox-active cofactor DBMIB bound to the full length circadian clock protein KaiA from Synechococcus elongatus

spinqualitylabelsall models 4g86, resolution 2.39Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4g86 is a 2 chain structure with sequence from Anacystis nidulans r2. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 1PE, 2PE, BNT, GOL Related: 1r8j Gene: kaiA, see0009, Synpcc7942_1218 (Anacystis nidulans R2) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [KAIA_SYNE7] Component of the KaiABC clock protein complex, which constitutes the main circadian regulator in cyanobacteria. The KaiABC complex may act as a promoter-nonspecific transcription regulator that represses transcription, possibly by acting on the state of chromosome compaction. In the complex, it enhances the phosphorylation status of KaiC. In contrast, the presence of KaiB in the complex decreases the phosphorylation status of KaiC, suggesting that KaiB acts by antagonizing the interaction between KaiA and KaiC. A KaiA dimer is sufficient to enhance KaiC hexamer phosphorylation. Publication Abstract from PubMed 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. 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.,Pattanayek R, Sidiqi SK, Egli M Biochemistry. 2012 Oct 5. PMID:23020633 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Circadian clock protein 3D structures

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