1suy
From Proteopedia
NMR structure of the ThKaiA180C-CIIABD complex (average minimized structure)
Structural highlights
Function[KAIA_THEEB] 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. [KAIC_THEEB] Core component of the KaiABC clock protein complex, which constitutes the main circadian regulator in cyanobacteria. Binds to DNA. The KaiABC complex may act as a promoter-nonspecific transcription regulator that represses transcription, possibly by acting on the state of chromosome compaction (By similarity).[HAMAP-Rule:MF_01836] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedCircadian clocks are widespread endogenous mechanisms that control the temporal pattern of diverse biological processes, including gene transcription. KaiA is the positive element of the cyanobacterial clock because KaiA overexpression elevates transcription levels of clock components. Recently, we showed that the structure of KaiA is that of a domain-swapped homodimer. The N-terminal domain is a pseudo-receiver; thus, it is likely to be involved in signal transduction in the clock-resetting pathway. The C-terminal domain of KaiA is structurally novel and enhances the KaiC autokinase activity directly. Here, we report the NMR structure of the C-terminal domain of KaiA (ThKaiA180C) in complex with a KaiC-derived peptide from the cyanobacterium Thermosynechococcus elongatus BP-1. The protein-peptide interface is revealed to be different from a model that was proposed earlier, is stabilized by a combination of hydrophobic and electrostatic interactions, and includes many residues known to produce a circadian-period phenotype upon substitution. Although the structure of the monomeric subunit of ThKaiA180C is largely unchanged upon peptide binding, the intersubunit dimerization angle changes. It is proposed that modulation of the C-terminal KaiA domain dimerization angle regulates KaiA-KaiC interactions. Structure of the C-terminal domain of the clock protein KaiA in complex with a KaiC-derived peptide: implications for KaiC regulation.,Vakonakis I, LiWang AC Proc Natl Acad Sci U S A. 2004 Jul 27;101(30):10925-30. Epub 2004 Jul 15. PMID:15256595[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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