Abstract：
:The circadian clock controls 24-h biological rhythms in our body, influencing many time-related activities such as sleep and wake. The simplest circadian clock is found in cyanobacteria, with the proteins KaiA, KaiB, and KaiC generating a self-sustained circadian oscillation of KaiC phosphorylation and dephosphorylation. KaiA activates KaiC phosphorylation by binding the A-loop of KaiC, while KaiB attenuates the phosphorylation by sequestering KaiA from the A-loop. Structural analysis revealed that magnesium regulates the phosphorylation and dephosphorylation of KaiC by dissociating from and associating with catalytic Glu residues that activate phosphorylation and dephosphorylation, respectively. High magnesium causes KaiC to dephosphorylate, whereas low magnesium causes KaiC to phosphorylate. KaiC alone behaves as an hourglass timekeeper when the magnesium concentration is alternated between low and high levels in vitro. We suggest that a magnesium-based hourglass timekeeping system may have been used by ancient cyanobacteria before magnesium homeostasis was established.
journal_name
J Biol Rhythmsjournal_title
Journal of biological rhythmsauthors
Jeong YM,Dias C,Diekman C,Brochon H,Kim P,Kaur M,Kim YS,Jang HI,Kim YIdoi
10.1177/0748730419851655subject
Has Abstractpub_date
2019-08-01 00:00:00pages
380-390issue
4eissn
0748-7304issn
1552-4531journal_volume
34pub_type
杂志文章abstract：:Austrovenus stutchburyi is an intertidal, burrowing, filter-feeding bivalve. It exhibits a strong, approximately tidal pattern in the time of gaping of its valves when in constant laboratory conditions. Individuals that have been held in laboratory conditions long enough to lose their overt gaping pattern will respond...
journal_title：Journal of biological rhythms
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