7S66

Extended conformation of nighttime state KaiC

Summary for 7S66

• Entry DOI: 10.2210/pdb7s66/pdb
• EMDB information: 24850 24851 24852
• Descriptor: Circadian clock protein kinase KaiC, ADENOSINE-5'-TRIPHOSPHATE, MAGNESIUM ION (3 entities in total)
• Functional Keywords: aaa atpase, circadian oscillator, kinase, phosphatase, circadian clock protein
• Biological source: Synechococcus elongatus
• Total number of polymer chains: 6
• Total formula weight: 354886.52

Authors

Sandate, C.R.,Swan, J.A.,Partch, C.L.,Lander, G.C. (deposition date: 2021-09-13, release date: 2021-09-22, Last modification date: 2024-06-05)

Primary citation

Swan, J.A.,Sandate, C.R.,Chavan, A.G.,Freeberg, A.M.,Etwaru, D.,Ernst, D.C.,Palacios, J.G.,Golden, S.S.,LiWang, A.,Lander, G.C.,Partch, C.L.
Coupling of distant ATPase domains in the circadian clock protein KaiC.
Nat.Struct.Mol.Biol., 29:759-766, 2022

PubMed Abstract: The AAA family member KaiC is the central pacemaker for circadian rhythms in the cyanobacterium Synechococcus elongatus. Composed of two hexameric rings of adenosine triphosphatase (ATPase) domains with tightly coupled activities, KaiC undergoes a cycle of autophosphorylation and autodephosphorylation on its C-terminal (CII) domain that restricts binding of clock proteins on its N-terminal (CI) domain to the evening. Here, we use cryogenic-electron microscopy to investigate how daytime and nighttime states of CII regulate KaiB binding on CI. We find that the CII hexamer is destabilized during the day but takes on a rigidified C-symmetric state at night, concomitant with ring-ring compression. Residues at the CI-CII interface are required for phospho-dependent KaiB association, coupling ATPase activity on CI to cooperative KaiB recruitment. Together, these studies clarify a key step in the regulation of cyanobacterial circadian rhythms by KaiC phosphorylation.

PubMed: 35864165
DOI: 10.1038/s41594-022-00803-w

Experimental method

ELECTRON MICROSCOPY (2.8 Å)