1
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Chavan A, Heisler J, Chang YG, Golden SS, Partch CL, LiWang A. Protocols for in vitro reconstitution of the cyanobacterial circadian clock. Biopolymers 2024; 115:e23559. [PMID: 37421636 PMCID: PMC10772220 DOI: 10.1002/bip.23559] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/26/2023] [Accepted: 06/16/2023] [Indexed: 07/10/2023]
Abstract
Circadian clocks are intracellular systems that orchestrate metabolic processes in anticipation of sunrise and sunset by providing an internal representation of local time. Because the ~24-h metabolic rhythms they produce are important to health across diverse life forms there is growing interest in their mechanisms. However, mechanistic studies are challenging in vivo due to the complex, that is, poorly defined, milieu of live cells. Recently, we reconstituted the intact circadian clock of cyanobacteria in vitro. It oscillates autonomously and remains phase coherent for many days with a fluorescence-based readout that enables real-time observation of individual clock proteins and promoter DNA simultaneously under defined conditions without user intervention. We found that reproducibility of the reactions required strict adherence to the quality of each recombinant clock protein purified from Escherichia coli. Here, we provide protocols for preparing in vitro clock samples so that other labs can ask questions about how changing environments, like temperature, metabolites, and protein levels are reflected in the core oscillator and propagated to regulation of transcription, providing deeper mechanistic insights into clock biology.
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Affiliation(s)
- Archana Chavan
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- School of Natural Sciences, University of California – Merced, Merced, CA 95343
| | - Joel Heisler
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- School of Natural Sciences, University of California – Merced, Merced, CA 95343
| | - Yong-Gang Chang
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- School of Natural Sciences, University of California – Merced, Merced, CA 95343
| | - Susan S. Golden
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- Department of Molecular Biology, University of California – San Diego, La Jolla, CA 92093
| | - Carrie L. Partch
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- Department of Chemistry & Biochemistry, University of California – Santa Cruz, Santa Cruz, CA 95064
| | - Andy LiWang
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- School of Natural Sciences, University of California – Merced, Merced, CA 95343
- Department of Chemistry & Biochemistry, University of California – Merced, Merced, CA 95343
- Center for Cellular and Biomolecular Machines, University of California – Merced, Merced, CA 95343
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2
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McKnight BM, Kang S, Le TH, Fang M, Carbonel G, Rodriguez E, Govindarajan S, Albocher-Kedem N, Tran AL, Duncan NR, Amster-Choder O, Golden SS, Cohen SE. Roles for the Synechococcus elongatus RNA-Binding Protein Rbp2 in Regulating the Circadian Clock. J Biol Rhythms 2023; 38:447-460. [PMID: 37515350 PMCID: PMC10528358 DOI: 10.1177/07487304231188761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
The cyanobacterial circadian oscillator, consisting of KaiA, KaiB, and KaiC proteins, drives global rhythms of gene expression and compaction of the chromosome and regulates the timing of cell division and natural transformation. While the KaiABC posttranslational oscillator can be reconstituted in vitro, the Kai-based oscillator is subject to several layers of regulation in vivo. Specifically, the oscillator proteins undergo changes in their subcellular localization patterns, where KaiA and KaiC are diffuse throughout the cell during the day and localized as a focus at or near the pole of the cell at night. Here, we report that the CI domain of KaiC, when in a hexameric state, is sufficient to target KaiC to the pole. Moreover, increased ATPase activity of KaiC correlates with enhanced polar localization. We identified proteins associated with KaiC in either a localized or diffuse state. We found that loss of Rbp2, found to be associated with localized KaiC, results in decreased incidence of KaiC localization and long-period circadian phenotypes. Rbp2 is an RNA-binding protein, and it appears that RNA-binding activity of Rbp2 is required to execute clock functions. These findings uncover previously unrecognized roles for Rbp2 in regulating the circadian clock and suggest that the proper localization of KaiC is required for a fully functional clock in vivo.
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Affiliation(s)
- Briana M. McKnight
- Department of Molecular Biology, University of California, San Diego, La Jolla, CA 92093
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093
| | - Shannon Kang
- Department of Molecular Biology, University of California, San Diego, La Jolla, CA 92093
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093
| | - Tam H. Le
- Department of Biological Sciences, California State University, Los Angeles, Los Angeles, CA 90032
| | - Mingxu Fang
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093
| | - Genelyn Carbonel
- Department of Biological Sciences, California State University, Los Angeles, Los Angeles, CA 90032
| | - Esbeydi Rodriguez
- Department of Biological Sciences, California State University, Los Angeles, Los Angeles, CA 90032
| | - Sutharsan Govindarajan
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, Jerusalem 91120, Israel
- Department of Biological Sciences, SRM University AP, Amaravati, India
| | - Nitsan Albocher-Kedem
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, Jerusalem 91120, Israel
| | - Amanda L. Tran
- Department of Biological Sciences, California State University, Los Angeles, Los Angeles, CA 90032
| | - Nicholas R. Duncan
- Department of Biological Sciences, California State University, Los Angeles, Los Angeles, CA 90032
| | - Orna Amster-Choder
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, Jerusalem 91120, Israel
| | - Susan S. Golden
- Department of Molecular Biology, University of California, San Diego, La Jolla, CA 92093
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093
| | - Susan E. Cohen
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093
- Department of Biological Sciences, California State University, Los Angeles, Los Angeles, CA 90032
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3
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Sasai M. Role of the reaction-structure coupling in temperature compensation of the KaiABC circadian rhythm. PLoS Comput Biol 2022; 18:e1010494. [PMID: 36067222 PMCID: PMC9481178 DOI: 10.1371/journal.pcbi.1010494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 09/16/2022] [Accepted: 08/17/2022] [Indexed: 11/19/2022] Open
Abstract
When the mixture solution of cyanobacterial proteins, KaiA, KaiB, and KaiC, is incubated with ATP in vitro, the phosphorylation level of KaiC shows stable oscillations with the temperature-compensated circadian period. Elucidating this temperature compensation is essential for understanding the KaiABC circadian clock, but its mechanism has remained a mystery. We analyzed the KaiABC temperature compensation by developing a theoretical model describing the feedback relations among reactions and structural transitions in the KaiC molecule. The model showed that the reduced structural cooperativity should weaken the negative feedback coupling among reactions and structural transitions, which enlarges the oscillation amplitude and period, explaining the observed significant period extension upon single amino-acid residue substitution. We propose that an increase in thermal fluctuations similarly attenuates the reaction-structure feedback, explaining the temperature compensation in the KaiABC clock. The model explained the experimentally observed responses of the oscillation phase to the temperature shift or the ADP-concentration change and suggested that the ATPase reactions in the CI domain of KaiC affect the period depending on how the reaction rates are modulated. The KaiABC clock provides a unique opportunity to analyze how the reaction-structure coupling regulates the system-level synchronized oscillations of molecules.
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Affiliation(s)
- Masaki Sasai
- Department of Applied Physics, Nagoya University, Nagoya, Japan
- Department of Complex Systems Science, Nagoya University, Nagoya, Japan
- Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto, Japan
- * E-mail:
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4
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Dimer dissociation is a key energetic event in the fold-switch pathway of KaiB. Biophys J 2022; 121:943-955. [PMID: 35151633 PMCID: PMC8943816 DOI: 10.1016/j.bpj.2022.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 12/14/2021] [Accepted: 02/09/2022] [Indexed: 11/21/2022] Open
Abstract
Cyanobacteria possesses the simplest circadian clock, composed of three proteins that act as a phosphorylation oscillator: KaiA, KaiB, and KaiC. The timing of this oscillator is determined by the fold-switch of KaiB, a structural rearrangement of its C-terminal half that is accompanied by a change in the oligomerization state. During the day, KaiB forms a stable tetramer (gsKaiB), whereas it adopts a monomeric thioredoxin-like fold during the night (fsKaiB). Although the structures and functions of both native states are well studied, little is known about the sequence and structure determinants that control their structural interconversion. Here, we used confinement molecular dynamics (CCR-MD) and folding simulations using structure-based models to show that the dissociation of the gsKaiB dimer is a key energetic event for the fold-switch. Hydrogen-deuterium exchange mass spectrometry (HDXMS) recapitulates the local stability of protein regions reported by CCR-MD, with both approaches consistently indicating that the energy and backbone flexibility changes are solely associated with the region that fold-switches between gsKaiB and fsKaiB and that the localized regions that differentially stabilize gsKaiB also involve regions outside the dimer interface. Moreover, two mutants (R23C and R75C) previously reported to be relevant for altering the rhythmicity of the Kai clock were also studied by HDXMS. Particularly, R75C populates dimeric and monomeric states with a deuterium incorporation profile comparable to the one observed for fsKaiB, emphasizing the importance of the oligomerization state of KaiB for the fold-switch. These findings suggest that the information necessary to control the rhythmicity of the cyanobacterial biological clock is, to a great extent, encoded within the KaiB sequence.
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5
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Simon D, Mukaiyama A, Furuike Y, Akiyama S. Slow and temperature-compensated autonomous disassembly of KaiB–KaiC complex. Biophys Physicobiol 2022; 19:1-11. [PMID: 35666689 PMCID: PMC9135616 DOI: 10.2142/biophysico.bppb-v19.0008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 03/28/2022] [Indexed: 12/01/2022] Open
Affiliation(s)
- Damien Simon
- Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, National Institutes of Natural Sciences
| | - Atsushi Mukaiyama
- Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, National Institutes of Natural Sciences
| | - Yoshihiko Furuike
- Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, National Institutes of Natural Sciences
| | - Shuji Akiyama
- Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, National Institutes of Natural Sciences
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6
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Mechanism of autonomous synchronization of the circadian KaiABC rhythm. Sci Rep 2021; 11:4713. [PMID: 33633230 PMCID: PMC7907350 DOI: 10.1038/s41598-021-84008-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 02/11/2021] [Indexed: 11/28/2022] Open
Abstract
The cyanobacterial circadian clock can be reconstituted by mixing three proteins, KaiA, KaiB, and KaiC, in vitro. In this protein mixture, oscillations of the phosphorylation level of KaiC molecules are synchronized to show the coherent oscillations of the ensemble of many molecules. However, the molecular mechanism of this synchronization has not yet been fully elucidated. In this paper, we explain a theoretical model that considers the multifold feedback relations among the structure and reactions of KaiC. The simulated KaiC hexamers show stochastic switch-like transitions at the level of single molecules, which are synchronized in the ensemble through the sequestration of KaiA into the KaiC–KaiB–KaiA complexes. The proposed mechanism quantitatively reproduces the synchronization that was observed by mixing two solutions oscillating in different phases. The model results suggest that biochemical assays with varying concentrations of KaiA or KaiB can be used to test this hypothesis.
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7
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Mutoh R, Iwata K, Iida T, Ishiura M, Onai K. Rhythmic adenosine triphosphate release from the cyanobacterial circadian clock protein KaiC revealed by real-time monitoring of bioluminescence using firefly luciferase. Genes Cells 2021; 26:83-93. [PMID: 33341998 DOI: 10.1111/gtc.12825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/16/2020] [Accepted: 12/16/2020] [Indexed: 11/27/2022]
Abstract
The cyanobacterial circadian clock is composed of three clock proteins, KaiA, KaiB and KaiC. This KaiABC clock system can be reconstituted in vitro in the presence of adenosine triphosphate (ATP) and Mg2+ , and shows circadian rhythms in the phosphorylation level and ATPase activity of KaiC. Previously, we found that ATP regulates a complex formation between KaiB and KaiC, and KaiC releases ATP from KaiC itself (PLoS One, 8, 2013, e80200). In this study, we examined whether the ATP release from KaiC shows any rhythms in vitro. We monitored the release of ATP from wild-type and ATPase motif mutants of KaiC as a bioluminescence in real time using a firefly luciferase assay in vitro and obtained the following results: (a) ATP release from KaiC oscillated even without KaiA and KaiB although period of the oscillation was not 24 hr; (b) ATP was mainly released from the N-terminal domain of KaiC; and (c) the ATP release was enhanced and suppressed by KaiB and KaiA, respectively. These results suggest that KaiC can generate basal oscillation as a core clock without KaiA and KaiB, whereas these two proteins contribute to adjusting and stabilizing the oscillation.
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Affiliation(s)
- Risa Mutoh
- Center for Gene Research, Nagoya University, Nagoya, Japan
| | - Keita Iwata
- Center for Gene Research, Nagoya University, Nagoya, Japan.,Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Takahiro Iida
- Center for Gene Research, Nagoya University, Nagoya, Japan
| | - Masahiro Ishiura
- Center for Gene Research, Nagoya University, Nagoya, Japan.,Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Kiyoshi Onai
- Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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8
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Hong L, Lavrentovich DO, Chavan A, Leypunskiy E, Li E, Matthews C, LiWang A, Rust MJ, Dinner AR. Bayesian modeling reveals metabolite-dependent ultrasensitivity in the cyanobacterial circadian clock. Mol Syst Biol 2020; 16:e9355. [PMID: 32496641 PMCID: PMC7271899 DOI: 10.15252/msb.20199355] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 04/21/2020] [Accepted: 04/24/2020] [Indexed: 12/22/2022] Open
Abstract
Mathematical models can enable a predictive understanding of mechanism in cell biology by quantitatively describing complex networks of interactions, but such models are often poorly constrained by available data. Owing to its relative biochemical simplicity, the core circadian oscillator in Synechococcus elongatus has become a prototypical system for studying how collective dynamics emerge from molecular interactions. The oscillator consists of only three proteins, KaiA, KaiB, and KaiC, and near-24-h cycles of KaiC phosphorylation can be reconstituted in vitro. Here, we formulate a molecularly detailed but mechanistically naive model of the KaiA-KaiC subsystem and fit it directly to experimental data within a Bayesian parameter estimation framework. Analysis of the fits consistently reveals an ultrasensitive response for KaiC phosphorylation as a function of KaiA concentration, which we confirm experimentally. This ultrasensitivity primarily results from the differential affinity of KaiA for competing nucleotide-bound states of KaiC. We argue that the ultrasensitive stimulus-response relation likely plays an important role in metabolic compensation by suppressing premature phosphorylation at nighttime.
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Affiliation(s)
- Lu Hong
- Graduate Program in Biophysical Sciences, University of Chicago, Chicago, IL, USA
| | | | - Archana Chavan
- School of Natural Sciences, University of California, Merced, CA, USA
| | - Eugene Leypunskiy
- Graduate Program in Biophysical Sciences, University of Chicago, Chicago, IL, USA
| | - Eileen Li
- Department of Statistics, University of Chicago, Chicago, IL, USA
| | - Charles Matthews
- Department of Statistics, University of Chicago, Chicago, IL, USA
| | - Andy LiWang
- School of Natural Sciences, University of California, Merced, CA, USA
- Quantitative and Systems Biology, University of California, Merced, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
- Chemistry and Chemical Biology, University of California, Merced, CA, USA
- Health Sciences Research Institute, University of California, Merced, CA, USA
- Center for Cellular and Biomolecular Machines, University of California, Merced, CA, USA
| | - Michael J Rust
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
- Institute for Genomics and Systems Biology, University of Chicago, Chicago, IL, USA
| | - Aaron R Dinner
- Department of Chemistry, University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
- James Franck Institute, University of Chicago, Chicago, IL, USA
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9
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Kawamoto N, Ito H, Tokuda IT, Iwasaki H. Damped circadian oscillation in the absence of KaiA in Synechococcus. Nat Commun 2020; 11:2242. [PMID: 32382052 PMCID: PMC7205874 DOI: 10.1038/s41467-020-16087-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 04/09/2020] [Indexed: 01/05/2023] Open
Abstract
Proteins KaiA, KaiB and KaiC constitute a biochemical circadian oscillator in the cyanobacterium Synechococcus elongatus. It has been reported kaiA inactivation completely abolishes circadian oscillations. However, we show here that kaiBC promoter activity exhibits a damped, low-amplitude oscillation with a period of approximately 24 h in kaiA-inactivated strains. The damped rhythm resonates with external cycles with a period of 24–26 h, indicating that its natural frequency is similar to that of the circadian clock. Double-mutation experiments reveal that kaiC, kaiB, and sasA (encoding a KaiC-binding histidine kinase) are all required for the damped oscillation. Further analysis suggests that the kaiA-less damped transcriptional rhythm requires KaiB-KaiC complex formation and the transcription-translation feedback loop, but not the KaiC phosphorylation cycle. Our results provide insights into mechanisms that could potentially underlie the diurnal/circadian behaviors observed in other bacterial species that possess kaiB and kaiC homologues but lack a kaiA homologue. Proteins KaiA, KaiB and KaiC constitute a biochemical circadian oscillator in Synechococcus cyanobacteria. Here, Kawamoto et al. show that kaiBC promoter activity exhibits a damped, low-amplitude circadian oscillation in the absence of KaiA, which could explain the circadian rhythms observed in other bacteria that lack a kaiA homologue.
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Affiliation(s)
- Naohiro Kawamoto
- Department of Electrical Engineering and Biological Science, Waseda University, Tokyo, 162-0056, Japan
| | - Hiroshi Ito
- Faculty of Design, Kyushu University, Fukuoka, 815-8540, Japan
| | - Isao T Tokuda
- Graduate School of Science and Engineering, Ritsumeikan University, Shiga, 525-8577, Japan
| | - Hideo Iwasaki
- Department of Electrical Engineering and Biological Science, Waseda University, Tokyo, 162-0056, Japan.
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10
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Partch CL. Orchestration of Circadian Timing by Macromolecular Protein Assemblies. J Mol Biol 2020; 432:3426-3448. [DOI: 10.1016/j.jmb.2019.12.046] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/13/2019] [Accepted: 12/18/2019] [Indexed: 12/13/2022]
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11
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Yunoki Y, Ishii K, Yagi-Utsumi M, Murakami R, Uchiyama S, Yagi H, Kato K. ATP hydrolysis by KaiC promotes its KaiA binding in the cyanobacterial circadian clock system. Life Sci Alliance 2019; 2:2/3/e201900368. [PMID: 31160381 PMCID: PMC6549140 DOI: 10.26508/lsa.201900368] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 12/01/2022] Open
Abstract
ATP hydrolysis in the KaiC hexamer triggers the exposure of its C-terminal segments into the solvent so as to capture KaiA, providing mechanistic insights into the circadian periodicity regulation. The cyanobacterial clock is controlled via the interplay among KaiA, KaiB, and KaiC, which generate a periodic oscillation of KaiC phosphorylation in the presence of ATP. KaiC forms a homohexamer harboring 12 ATP-binding sites and exerts ATPase activities associated with its autophosphorylation and dephosphorylation. The KaiC nucleotide state is a determining factor of the KaiB–KaiC interaction; however, its relationship with the KaiA–KaiC interaction has not yet been elucidated. With the attempt to address this, our native mass spectrometric analyses indicated that ATP hydrolysis in the KaiC hexamer promotes its interaction with KaiA. Furthermore, our nuclear magnetic resonance spectral data revealed that ATP hydrolysis is coupled with conformational changes in the flexible C-terminal segments of KaiC, which carry KaiA-binding sites. From these data, we conclude that ATP hydrolysis in KaiC is coupled with the exposure of its C-terminal KaiA-binding sites, resulting in its high affinity for KaiA. These findings provide mechanistic insights into the ATP-mediated circadian periodicity.
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Affiliation(s)
- Yasuhiro Yunoki
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Japan
| | - Kentaro Ishii
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Japan
| | - Maho Yagi-Utsumi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Japan
| | - Reiko Murakami
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Susumu Uchiyama
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Japan.,Department of Biotechnology, Graduate School of Engineering, Osaka University, Osaka, Japan
| | - Hirokazu Yagi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Koichi Kato
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan .,Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Japan
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12
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Sasai M. Effects of Stochastic Single-Molecule Reactions on Coherent Ensemble Oscillations in the KaiABC Circadian Clock. J Phys Chem B 2019; 123:702-713. [PMID: 30629448 DOI: 10.1021/acs.jpcb.8b10584] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
How do many constituent molecules in a biochemical system synchronize, giving rise to coherent system-level oscillations? One system that is particularly suitable for use in studying this problem is a mixture solution of three cyanobacterial proteins, KaiA, KaiB, and KaiC: the phosphorylation level of KaiC shows stable oscillations with a period of approximately 24 h when these three Kai proteins are incubated with ATP in vitro. Here, we analyze the mechanism behind synchronization in the KaiABC system theoretically by enhancing a model previously developed by the present author. Our simulation results suggest that positive feedback between stochastic ATP hydrolysis and the allosteric structural transitions in KaiC molecules drives oscillations of individual molecules and promotes synchronization of oscillations of many KaiC molecules. Our simulations also show that the ATPase activity of KaiC is correlated with the oscillation frequency of an ensemble of KaiC molecules. These results suggest that stochastic ATP hydrolysis in each KaiC molecule plays an important role in regulating the coherent system-level oscillations. This property is robust against changes in the binding and unbinding rate constants for KaiA to/from KaiC or KaiB, but the oscillations are sensitive to the rate constants of the KaiC phosphorylation and dephosphorylation reactions.
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Affiliation(s)
- Masaki Sasai
- Department of Applied Physics , Nagoya University , Nagoya 464-8603 , Japan
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13
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Abstract
Life has adapted to Earth's day-night cycle with the evolution of endogenous biological clocks. Whereas these circadian rhythms typically involve extensive transcription-translation feedback in higher organisms, cyanobacteria have a circadian clock, which functions primarily as a protein-based post-translational oscillator. Known as the Kai system, it consists of three proteins KaiA, KaiB, and KaiC. In this chapter, we provide a detailed structural overview of the Kai components and how they interact to produce circadian rhythms of global gene expression in cyanobacterial cells. We discuss how the circadian oscillation is coupled to gene expression, intertwined with transcription-translation feedback mechanisms, and entrained by input from the environment. We discuss the use of mathematical models and summarize insights into the cyanobacterial circadian clock from theoretical studies. The molecular details of the Kai system are well documented for the model cyanobacterium Synechococcus elongatus, but many less understood varieties of the Kai system exist across the highly diverse phylum of Cyanobacteria. Several species contain multiple kai-gene copies, while others like marine Prochlorococcus strains have a reduced kaiBC-only system, lacking kaiA. We highlight recent findings on the genomic distribution of kai genes in Bacteria and Archaea and finally discuss hypotheses on the evolution of the Kai system.
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Affiliation(s)
- Joost Snijder
- Snijder Bioscience, Zevenwouden 143, 3524CN, Utrecht, The Netherlands
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Ilka Maria Axmann
- Synthetic Microbiology, Biology Department, Heinrich Heine University Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany.
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14
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Hong L, Vani BP, Thiede EH, Rust MJ, Dinner AR. Molecular dynamics simulations of nucleotide release from the circadian clock protein KaiC reveal atomic-resolution functional insights. Proc Natl Acad Sci U S A 2018; 115:E11475-E11484. [PMID: 30442665 PMCID: PMC6298084 DOI: 10.1073/pnas.1812555115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The cyanobacterial clock proteins KaiA, KaiB, and KaiC form a powerful system to study the biophysical basis of circadian rhythms, because an in vitro mixture of the three proteins is sufficient to generate a robust ∼24-h rhythm in the phosphorylation of KaiC. The nucleotide-bound states of KaiC critically affect both KaiB binding to the N-terminal domain (CI) and the phosphotransfer reactions that (de)phosphorylate the KaiC C-terminal domain (CII). However, the nucleotide exchange pathways associated with transitions among these states are poorly understood. In this study, we integrate recent advances in molecular dynamics methods to elucidate the structure and energetics of the pathway for Mg·ADP release from the CII domain. We find that nucleotide release is coupled to large-scale conformational changes in the KaiC hexamer. Solvating the nucleotide requires widening the subunit interface leading to the active site, which is linked to extension of the A-loop, a structure implicated in KaiA binding. These results provide a molecular hypothesis for how KaiA acts as a nucleotide exchange factor. In turn, structural parallels between the CI and CII domains suggest a mechanism for allosteric coupling between the domains. We relate our results to structures observed for other hexameric ATPases, which perform diverse functions.
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Affiliation(s)
- Lu Hong
- Graduate Program in Biophysical Sciences, The University of Chicago, Chicago, IL 60637
| | - Bodhi P Vani
- Department of Chemistry, The University of Chicago, Chicago, IL 60637
| | - Erik H Thiede
- Department of Chemistry, The University of Chicago, Chicago, IL 60637
| | - Michael J Rust
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637;
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637
- Institute for Genomics and Systems Biology, The University of Chicago, Chicago, IL 60637
| | - Aaron R Dinner
- Department of Chemistry, The University of Chicago, Chicago, IL 60637;
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637
- James Franck Institute, The University of Chicago, Chicago, IL 60637
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15
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Conformational rearrangements of the C1 ring in KaiC measure the timing of assembly with KaiB. Sci Rep 2018; 8:8803. [PMID: 29892030 PMCID: PMC5995851 DOI: 10.1038/s41598-018-27131-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/25/2018] [Indexed: 01/26/2023] Open
Abstract
KaiC, the core oscillator of the cyanobacterial circadian clock, is composed of an N-terminal C1 domain and a C-terminal C2 domain, and assembles into a double-ring hexamer upon ATP binding. Cyclic phosphorylation and dephosphorylation at Ser431 and Thr432 in the C2 domain proceed with a period of approximately 24 h in the presence of other clock proteins, KaiA and KaiB, but recent studies have revealed a crucial role for the C1 ring in determining the cycle period. In this study, we mapped dynamic structural changes of the C1 ring in solution using a combination of site-directed tryptophan mutagenesis and fluorescence spectroscopy. We found that the C1 ring undergoes a structural transition, coupled with ATPase activity and the phosphorylation state, while maintaining its hexameric ring structure. This transition triggered by ATP hydrolysis in the C1 ring in specific phosphorylation states is a necessary event for recruitment of KaiB, limiting the overall rate of slow complex formation. Our results provide structural and kinetic insights into the C1-ring rearrangements governing the slow dynamics of the cyanobacterial circadian clock.
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16
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Das S, Terada TP, Sasai M. Single-molecular and ensemble-level oscillations of cyanobacterial circadian clock. Biophys Physicobiol 2018; 15:136-150. [PMID: 29955565 PMCID: PMC6018440 DOI: 10.2142/biophysico.15.0_136] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 04/10/2018] [Indexed: 01/15/2023] Open
Abstract
When three cyanobacterial proteins, KaiA, KaiB, and KaiC, are incubated with ATP in vitro, the phosphorylation level of KaiC hexamers shows stable oscillation with approximately 24 h period. In order to understand this KaiABC clockwork, we need to analyze both the macroscopic synchronization of a large number of KaiC hexamers and the microscopic reactions and structural changes in individual KaiC molecules. In the present paper, we explain two coarse-grained theoretical models, the many-molecule (MM) model and the single-molecule (SM) model, to bridge the gap between macroscopic and microscopic understandings. In the simulation results with these models, ATP hydrolysis in the CI domain of KaiC hexamers drives oscillation of individual KaiC hexamers and the ATP hydrolysis is necessary for synchronizing oscillations of a large number of KaiC hexamers. Sensitive temperature dependence of the lifetime of the ADP bound state in the CI domain makes the oscillation period temperature insensitive. ATPase activity is correlated to the frequency of phosphorylation oscillation in the single molecule of KaiC hexamer, which should be the origin of the observed ensemble-level correlation between the ATPase activity and the frequency of phosphorylation oscillation. Thus, the simulation results with the MM and SM models suggest that ATP hydrolysis stochastically occurring in each CI domain of individual KaiC hexamers is a key process for oscillatory behaviors of the ensemble of many KaiC hexamers.
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Affiliation(s)
- Sumita Das
- Department of Computational Science and Engineering and Department of Applied Physics, Nagoya University, Nagoya, Aichi 464-8603, Japan
| | - Tomoki P Terada
- Department of Computational Science and Engineering and Department of Applied Physics, Nagoya University, Nagoya, Aichi 464-8603, Japan
| | - Masaki Sasai
- Department of Computational Science and Engineering and Department of Applied Physics, Nagoya University, Nagoya, Aichi 464-8603, Japan
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17
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Murakami R, Hokonohara H, Che DC, Kawai T, Matsumoto T, Ishiura M. Atomic force microscopy analysis of SasA-KaiC complex formation involved in information transfer from the KaiABC clock machinery to the output pathway in cyanobacteria. Genes Cells 2018. [PMID: 29527779 DOI: 10.1111/gtc.12574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cyanobacterial clock oscillator is composed of three clock proteins: KaiA, KaiB and KaiC. SasA, a KaiC-binding EnvZ-like orthodox histidine kinase involved in the main clock output pathway, exists mainly as a trimer (SasA3mer ) and occasionally as a hexamer (SasA6mer ) in vitro. Previously, the molecular mass of the SasA-KaiCDD complex, where KaiCDD is a mutant KaiC with two Asp substitutions at the two phosphorylation sites, has been estimated by gel-filtration chromatography to be larger than 670 kDa. This value disagrees with the theoretical estimation of 480 kDa for a SasA3mer -KaiC hexamer (KaiC6mer ) complex with a 1:1 molecular ratio. To clarify the structure of the SasA-KaiC complex, we analyzed KaiCDD with 0.1 mmol/L ATP and 5 mmol/L MgCl2 (Mg-ATP), SasA and a mixture containing SasA and KaiCDD6mer with Mg-ATP by atomic force microscopy (AFM). KaiCDD images were classified into two types with height distribution corresponding to KaiCDD monomer (KaiCDD1mer ) and KaiCDD6mer , respectively. SasA images were classified into two types with height corresponding to SasA3mer and SasA6mer , respectively. The AFM images of the SasA-KaiCDD mixture indicated not only KaiCDD1mer , KaiCDD6mer , SasA3mer and SasA6mer , but also wider area "islands," suggesting the presence of a polymerized form of the SasA-KaiCDD complex.
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Affiliation(s)
- Reiko Murakami
- Center for Gene Research, Nagoya University, Nagoya, Japan.,Division of Biological Sciences, Nagoya University, Nagoya, Japan
| | - Hitomi Hokonohara
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.,Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan
| | - Dock-Chil Che
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Tomoji Kawai
- Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan
| | - Takuya Matsumoto
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Masahiro Ishiura
- Center for Gene Research, Nagoya University, Nagoya, Japan.,Division of Biological Sciences, Nagoya University, Nagoya, Japan
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18
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Das S, Terada TP, Sasai M. Role of ATP Hydrolysis in Cyanobacterial Circadian Oscillator. Sci Rep 2017; 7:17469. [PMID: 29234156 PMCID: PMC5727317 DOI: 10.1038/s41598-017-17717-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/29/2017] [Indexed: 12/11/2022] Open
Abstract
A cyanobacterial protein KaiC shows a stable oscillation in its phosphorylation level with approximately one day period when three proteins, KaiA, KaiB, and KaiC, are incubated in the presence of ATP in vitro. During this oscillation, KaiC hydrolyzes more ATP molecules than required for phosphorylation. Here, in this report, a theoretical model of the KaiABC oscillator is developed to elucidate the role of this ATP consumption by assuming multifold feedback relations among reactions and structural transition in each KaiC molecule and the structure-dependent binding reactions among Kai proteins. Results of numerical simulation showed that ATP hydrolysis is a driving mechanism of the phosphorylation oscillation in the present model, and that the frequency of ATP hydrolysis in individual KaiC molecules is correlated to the frequency of oscillation in the ensemble of many Kai molecules, which indicates that the coherent oscillation is generated through the coupled microscopic intramolecular and ensemble-level many-molecular regulations.
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Affiliation(s)
- Sumita Das
- Department of Computational Science and Engineering, Nagoya University, Nagoya, 464-8603, Japan
| | - Tomoki P Terada
- Department of Computational Science and Engineering, Nagoya University, Nagoya, 464-8603, Japan.,Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
| | - Masaki Sasai
- Department of Computational Science and Engineering, Nagoya University, Nagoya, 464-8603, Japan. .,Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan.
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19
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Tseng R, Goularte NF, Chavan A, Luu J, Cohen SE, Chang YG, Heisler J, Li S, Michael AK, Tripathi S, Golden SS, LiWang A, Partch CL. Structural basis of the day-night transition in a bacterial circadian clock. Science 2017; 355:1174-1180. [PMID: 28302851 PMCID: PMC5441561 DOI: 10.1126/science.aag2516] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 02/13/2017] [Indexed: 12/14/2022]
Abstract
Circadian clocks are ubiquitous timing systems that induce rhythms of biological activities in synchrony with night and day. In cyanobacteria, timing is generated by a posttranslational clock consisting of KaiA, KaiB, and KaiC proteins and a set of output signaling proteins, SasA and CikA, which transduce this rhythm to control gene expression. Here, we describe crystal and nuclear magnetic resonance structures of KaiB-KaiC,KaiA-KaiB-KaiC, and CikA-KaiB complexes. They reveal how the metamorphic properties of KaiB, a protein that adopts two distinct folds, and the post-adenosine triphosphate hydrolysis state of KaiC create a hub around which nighttime signaling events revolve, including inactivation of KaiA and reciprocal regulation of the mutually antagonistic signaling proteins, SasA and CikA.
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Affiliation(s)
- Roger Tseng
- Quantitative and Systems Biology, University of California, Merced, CA 95343, USA
| | - Nicolette F Goularte
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Archana Chavan
- School of Natural Sciences, University of California, Merced, CA 95343, USA
| | - Jansen Luu
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Susan E Cohen
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yong-Gang Chang
- School of Natural Sciences, University of California, Merced, CA 95343, USA
| | - Joel Heisler
- Chemistry and Chemical Biology, University of California, Merced, CA 95343, USA
| | - Sheng Li
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Alicia K Michael
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Sarvind Tripathi
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Susan S Golden
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Andy LiWang
- Quantitative and Systems Biology, University of California, Merced, CA 95343, USA.
- School of Natural Sciences, University of California, Merced, CA 95343, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA
- Chemistry and Chemical Biology, University of California, Merced, CA 95343, USA
- Health Sciences Research Institute, University of California, Merced, CA 95343, USA
| | - Carrie L Partch
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA
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20
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Sugiyama M, Yagi H, Ishii K, Porcar L, Martel A, Oyama K, Noda M, Yunoki Y, Murakami R, Inoue R, Sato N, Oba Y, Terauchi K, Uchiyama S, Kato K. Structural characterization of the circadian clock protein complex composed of KaiB and KaiC by inverse contrast-matching small-angle neutron scattering. Sci Rep 2016; 6:35567. [PMID: 27752127 PMCID: PMC5067715 DOI: 10.1038/srep35567] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/30/2016] [Indexed: 11/26/2022] Open
Abstract
The molecular machinery of the cyanobacterial circadian clock consists of three proteins: KaiA, KaiB, and KaiC. Through interactions among the three Kai proteins, the phosphorylation states of KaiC generate circadian oscillations in vitro in the presence of ATP. Here, we characterized the complex formation between KaiB and KaiC using a phospho-mimicking mutant of KaiC, which had an aspartate substitution at the Ser431 phosphorylation site and exhibited optimal binding to KaiB. Mass-spectrometric titration data showed that the proteins formed a complex exclusively in a 6:6 stoichiometry, indicating that KaiB bound to the KaiC hexamer with strong positive cooperativity. The inverse contrast-matching technique of small-angle neutron scattering enabled selective observation of KaiB in complex with the KaiC mutant with partial deuteration. It revealed a disk-shaped arrangement of the KaiB subunits on the outer surface of the KaiC C1 ring, which also serves as the interaction site for SasA, a histidine kinase that operates as a clock-output protein in the regulation of circadian transcription. These data suggest that cooperatively binding KaiB competes with SasA with respect to interaction with KaiC, thereby promoting the synergistic release of this clock-output protein from the circadian oscillator complex.
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Affiliation(s)
- Masaaki Sugiyama
- Research Reactor Institute, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Hirokazu Yagi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Kentaro Ishii
- Okazaki Institute for Integrative Bioscience and 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Lionel Porcar
- Institut Laue-Langevin, 71, Avenue des Martyrs, Grenoble 38042, France
| | - Anne Martel
- Institut Laue-Langevin, 71, Avenue des Martyrs, Grenoble 38042, France
| | - Katsuaki Oyama
- Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Masanori Noda
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuhiro Yunoki
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Reiko Murakami
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Rintaro Inoue
- Research Reactor Institute, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Nobuhiro Sato
- Research Reactor Institute, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Yojiro Oba
- Research Reactor Institute, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Kazuki Terauchi
- Graduate School of Life Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Susumu Uchiyama
- Okazaki Institute for Integrative Bioscience and 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.,Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Koichi Kato
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.,Okazaki Institute for Integrative Bioscience and 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.,Institute for Molecular Sciences, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
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21
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Conversion between two conformational states of KaiC is induced by ATP hydrolysis as a trigger for cyanobacterial circadian oscillation. Sci Rep 2016; 6:32443. [PMID: 27580682 PMCID: PMC5007536 DOI: 10.1038/srep32443] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/03/2016] [Indexed: 11/12/2022] Open
Abstract
The cyanobacterial circadian oscillator can be reconstituted in vitro by mixing three clock proteins, KaiA, KaiB and KaiC, with ATP. KaiC is the only protein with circadian rhythmic activities. In the present study, we tracked the complex formation of the three Kai proteins over time using blue native (BN) polyacrylamide gel electrophoresis (PAGE), in which proteins are charged with the anionic dye Coomassie brilliant blue (CBB). KaiC was separated as three bands: the KaiABC complex, KaiC hexamer and KaiC monomer. However, no KaiC monomer was observed using gel filtration chromatography and CBB-free native PAGE. These data indicate two conformational states of KaiC hexamer and show that the ground-state KaiC (gs-KaiC) is stable and competent-state KaiC (cs-KaiC) is labile and degraded into monomers by the binding of CBB. Repeated conversions from gs-KaiC to cs-KaiC were observed over 24 h using an in vitro reconstitution system. Phosphorylation of KaiC promoted the conversion from gs-KaiC to cs-KaiC. KaiA sustained the gs-KaiC state, and KaiB bound only cs-KaiC. An E77Q/E78Q-KaiC variant that lacked N-terminal ATPase activity remained in the gs-KaiC state. Taken together, ATP hydrolysis induces the formation of cs-KaiC and promotes the binding of KaiB, which is a trigger for circadian oscillations.
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22
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Murakami R, Mutoh R, Ishii K, Ishiura M. Circadian oscillations of KaiA-KaiC and KaiB-KaiC complex formations in an in vitro
reconstituted KaiABC clock oscillator. Genes Cells 2016; 21:890-900. [DOI: 10.1111/gtc.12392] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/31/2016] [Indexed: 11/27/2022]
Affiliation(s)
- Reiko Murakami
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya 464-8602 Japan
| | - Risa Mutoh
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya 464-8602 Japan
| | - Ketaro Ishii
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya 464-8602 Japan
| | - Masahiro Ishiura
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya 464-8602 Japan
- Division of Biological Sciences; Nagoya University; Furo-cho Chikusa Nagoya 464-8602 Japan
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23
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Iida T, Mutoh R, Onai K, Morishita M, Furukawa Y, Namba K, Ishiura M. Importance of the monomer-dimer-tetramer interconversion of the clock protein KaiB in the generation of circadian oscillations in cyanobacteria. Genes Cells 2014; 20:173-90. [DOI: 10.1111/gtc.12211] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 10/30/2014] [Indexed: 01/15/2023]
Affiliation(s)
- Takahiro Iida
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya Aichi 464-8602 Japan
- Division of Biological Science; Graduate School of Science; Nagoya University; Furo-cho Chikusa-ku Nagoya Aichi 464-8602 Japan
| | - Risa Mutoh
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya Aichi 464-8602 Japan
- Division of Biological Science; Graduate School of Science; Nagoya University; Furo-cho Chikusa-ku Nagoya Aichi 464-8602 Japan
| | - Kiyoshi Onai
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya Aichi 464-8602 Japan
| | - Megumi Morishita
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya Aichi 464-8602 Japan
| | - Yukio Furukawa
- Graduate School of Frontier Biosciences; Osaka University; 3-2 Yamadaoka Suita Osaka 565-0871 Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences; Osaka University; 3-2 Yamadaoka Suita Osaka 565-0871 Japan
| | - Masahiro Ishiura
- Center for Gene Research; Nagoya University; Furo-cho Chikusa-ku Nagoya Aichi 464-8602 Japan
- Division of Biological Science; Graduate School of Science; Nagoya University; Furo-cho Chikusa-ku Nagoya Aichi 464-8602 Japan
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24
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Abstract
Structural approaches have provided insight into the mechanisms of circadian clock oscillators. This review focuses upon the myriad structural methods that have been applied to the molecular architecture of cyanobacterial circadian proteins, their interactions with each other, and the mechanism of the KaiABC posttranslational oscillator. X-ray crystallography and solution NMR were deployed to gain an understanding of the three-dimensional structures of the three proteins KaiA, KaiB, and KaiC that make up the inner timer in cyanobacteria. A hybrid structural biology approach including crystallography, electron microscopy, and solution scattering has shed light on the shapes of binary and ternary Kai protein complexes. Structural studies of the cyanobacterial oscillator demonstrate both the strengths and the limitations of the divide-and-conquer strategy. Thus, investigations of complexes involving domains and/or peptides have afforded valuable information into Kai protein interactions. However, high-resolution structural data are still needed at the level of complexes between the 360-kDa KaiC hexamer that forms the heart of the clock and its KaiA and KaiB partners.
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25
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Egli M. Intricate protein-protein interactions in the cyanobacterial circadian clock. J Biol Chem 2014; 289:21267-75. [PMID: 24936066 DOI: 10.1074/jbc.r114.579607] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cyanobacterial circadian clock consists of a post-translational oscillator (PTO) and a PTO-dependent transcription-translation feedback loop (TTFL). The PTO can be reconstituted in vitro with the KaiA, KaiB, and KaiC proteins, enabling detailed biochemical and biophysical investigations. Both the CI and the CII halves of the KaiC hexamer harbor ATPases, but only the C-terminal CII ring exhibits kinase and phospho-transferase activities. KaiA stimulates the kinase and KaiB associates with KaiC during the dephosphorylation phase and sequesters KaiA. Recent research has led to conflicting models of the KaiB-KaiC interaction, precluding a clear understanding of KaiB function and KaiABC clock mechanism.
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Affiliation(s)
- Martin Egli
- From the Department of Biochemistry and Center for Structural Biology, Vanderbilt University, School of Medicine, Nashville, Tennessee 37232-0146
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26
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Pattanayek R, Xu Y, Lamichhane A, Johnson CH, Egli M. An arginine tetrad as mediator of input-dependent and input-independent ATPases in the clock protein KaiC. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:1375-90. [PMID: 24816106 PMCID: PMC4722857 DOI: 10.1107/s1399004714003228] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 02/12/2014] [Indexed: 11/10/2022]
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.
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Affiliation(s)
- Rekha Pattanayek
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
| | - Yao Xu
- Department of Biological Sciences, College of Arts and Science, Vanderbilt University, Nashville, TN 35235, USA
| | - Aashish Lamichhane
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
| | - Carl H. Johnson
- Department of Biological Sciences, College of Arts and Science, Vanderbilt University, Nashville, TN 35235, USA
| | - Martin Egli
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
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27
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Ishii K, Terauchi S, Murakami R, Valencia Swain J, Mutoh R, Mino H, Maki K, Arata T, Ishiura M. Site-directed spin labeling-electron spin resonance mapping of the residues of cyanobacterial clock protein KaiA that are affected by KaiA-KaiC interaction. Genes Cells 2014; 19:297-324. [PMID: 24495257 DOI: 10.1111/gtc.12130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 12/12/2013] [Indexed: 11/28/2022]
Abstract
The cyanobacterial clock proteins KaiA, KaiB and KaiC interact with each other to generate circadian oscillations. We have identified the residues of the KaiA homodimer affected through association with hexameric KaiC (KaiC6mer) using a spin-label-tagged KaiA C-terminal domain protein (KaiAc) and performing electron spin resonance (ESR) analysis. Cys substitution and/or the attachment of a spin label to residues located at the bottom area of the KaiAc concave surface, a KaiC-binding groove, hindered the association of KaiAc with KaiC6mer, suggesting that the groove likely mediates the interaction with KaiC6mer. The residues affected by KaiC6mer association were concentrated in the three areas: the concave surface, a lobe-like structure (a mobile lobe near the concave surface) and a region adjacent to both the concave surface and the mobile lobe. The distance between the two E254, D255, L258 and R252 residues located on the mobile lobe decreased after KaiC association, suggesting that the two mobile lobes approach each other during the interaction. Analyzing the molecular dynamics of KaiAc showed that these structural changes suggested by ESR analysis were possible. Furthermore, the analyses identified three asymmetries in KaiAc dynamic structures, which gave us a possible explanation of an asymmetric association of KaiAc with KaiC6mer.
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Affiliation(s)
- Kentaro Ishii
- Center for Gene Research, Nagoya University, Furo, Chikusa, Nagoya, Aichi, 464-8602, Japan; Division of Biological Science, Graduate School of Science, Osaka University, Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
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