title: An arginine tetrad as mediator of input-dependent and input-independent ATPases in the clock protein KaiC.
abstract: A post-translational oscillator (PTO) composed of the proteins KaiA, KaiB and KaiC is at the heart of the cyanobacterial circadian clock. KaiC interacts with KaiA and KaiB over the daily cycle, and CII domains undergo rhythmic phosphorylation/dephosphorylation with a 24 h period. Both the N-terminal (CI) and C-terminal (CII) rings of KaiC exhibit ATPase activity. The CI ATPase proceeds in an input-independent fashion, but the CII ATPase is subject to metabolic input signals. The crystal structure of KaiC from Thermosynechococcus elongatus allows insight into the different anatomies of the CI and CII ATPases. Four consecutive arginines in CI (Arg linker) that connect the P-loop, CI subunits and CI and CII at the ring interface are primary candidates for the coordination of the CI and CII activities. The mutation of linker residues alters the period or triggers arhythmic behavior. Comparison between the CI and CII structures also reveals differences in loop regions that are key to KaiA and KaiB binding and activation of CII ATPase and kinase. Common packing features in KaiC crystals shed light on the KaiB-KaiC interaction.
authors.affiliation: Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Rekha
authors.initials: R
authors.lastname: Pattanayek
authors.affiliation: Department of Biological Sciences, College of Arts and Science, Vanderbilt University, Nashville, TN 35235, USA.
authors.forename: Yao
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Aashish
authors.initials: A
authors.lastname: Lamichhane
authors.affiliation: Department of Biological Sciences, College of Arts and Science, Vanderbilt University, Nashville, TN 35235, USA.
authors.forename: Carl H
authors.initials: CH
authors.lastname: Johnson
authors.affiliation: Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Egli
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry; D001120:Arginine / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D046940:Synechococcus / Q000201:enzymology
chemical_list: D001426:Bacterial Proteins; D056925:Circadian Rhythm Signaling Peptides and Proteins; C114270:KaiB protein, cyanobacteria; C114271:KaiC protein, cyanobacteria; D001120:Arginine; D000251:Adenosine Triphosphatases
keywords: ATPase; KaiABC; circadian clock; kinase