Circadian clock oscillator protein KaiC

UniProtKB accession:  Q79PF4

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UniProtKB description:  The KaiABC oscillator complex constitutes the main circadian regulator in cyanobacteria (PubMed:15831759, PubMed:17717528, PubMed:26113637, PubMed:28302852, PubMed:9727980). Complex composition changes during the circadian cycle to control KaiC phosphorylation; KaiA stimulates KaiC autophosphorylation, while KaiB sequesters KaiA, leading to KaiC autodephosphorylation (PubMed:26113637, PubMed:28302852). The Kai complex controls chromosome condensation, leading to a transcription accessible chromosome during the first half of the circadian cycle and a compact, less transcription-accessible chromosome during the latter half (PubMed:16707582). Clock output pathways impact the RpaA transcriptional regulator (PubMed:20133618, PubMed:26113637, PubMed:28302852). Circadian oscillations can be generated in vitro by incubating KaiA, KaiB and KaiC with 1 mM ATP. The cycle is self-sustainable for at least 3 cycles and resistant to temperature changes. Mutations in KaiC alone prolong or reduce the circadian rhythm (PubMed:15831759). A very robust clock is reconstituted with KaiA, KaiB, KaiC, SasA, CikA and RpaA; output is measured by transcription from an appropriate reporter (PubMed:34618577).