4tle
From Proteopedia
Crystal structure of N-terminal C1 domain of KaiC
Structural highlights
Function[KAIC_SYNE7] 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.[1] [2] Publication Abstract from PubMedCircadian clocks generate slow and ordered cellular dynamics, but consist of fast-moving bio-macromolecules; consequently, the origins of the overall slowness remain unclear. We identified the adenosine triphosphate catalytic region (ATPase) in the N-terminal half of the clock protein KaiC as the minimal pacemaker that controls the in vivo frequency of the cyanobacterial clock. Crystal structures of the ATPase revealed that the slowness of this ATPase arises from sequestration of a lytic water molecule in an unfavorable position and coupling of ATP hydrolysis to a peptide isomerization with high activation energy. The slow ATPase is coupled with another ATPase catalyzing autodephosphorylation in the C-terminal half of KaiC, yielding the circadian response frequency of intermolecular interactions with other clock-related proteins that influences the transcription and translation cycle. Atomic-scale origins of slowness in the cyanobacterial circadian clock.,Abe J, Hiyama TB, Mukaiyama A, Son S, Mori T, Saito S, Osako M, Wolanin J, Yamashita E, Kondo T, Akiyama S Science. 2015 Jun 25. pii: 1261040. PMID:26113637[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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