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Dunkelmann DL, Chin JW. Engineering Pyrrolysine Systems for Genetic Code Expansion and Reprogramming. Chem Rev 2024. [PMID: 39235427 DOI: 10.1021/acs.chemrev.4c00243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2024]
Abstract
Over the past 16 years, genetic code expansion and reprogramming in living organisms has been transformed by advances that leverage the unique properties of pyrrolysyl-tRNA synthetase (PylRS)/tRNAPyl pairs. Here we summarize the discovery of the pyrrolysine system and describe the unique properties of PylRS/tRNAPyl pairs that provide a foundation for their transformational role in genetic code expansion and reprogramming. We describe the development of genetic code expansion, from E. coli to all domains of life, using PylRS/tRNAPyl pairs, and the development of systems that biosynthesize and incorporate ncAAs using pyl systems. We review applications that have been uniquely enabled by the development of PylRS/tRNAPyl pairs for incorporating new noncanonical amino acids (ncAAs), and strategies for engineering PylRS/tRNAPyl pairs to add noncanonical monomers, beyond α-L-amino acids, to the genetic code of living organisms. We review rapid progress in the discovery and scalable generation of mutually orthogonal PylRS/tRNAPyl pairs that can be directed to incorporate diverse ncAAs in response to diverse codons, and we review strategies for incorporating multiple distinct ncAAs into proteins using mutually orthogonal PylRS/tRNAPyl pairs. Finally, we review recent advances in the encoded cellular synthesis of noncanonical polymers and macrocycles and discuss future developments for PylRS/tRNAPyl pairs.
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Affiliation(s)
- Daniel L Dunkelmann
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, England, United Kingdom
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Jason W Chin
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, England, United Kingdom
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2
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Evans JA, Schwartz WJ. On the origin and evolution of the dual oscillator model underlying the photoperiodic clockwork in the suprachiasmatic nucleus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2024; 210:503-511. [PMID: 37481773 PMCID: PMC10924288 DOI: 10.1007/s00359-023-01659-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/07/2023] [Accepted: 07/13/2023] [Indexed: 07/25/2023]
Abstract
Decades have now passed since Colin Pittendrigh first proposed a model of a circadian clock composed of two coupled oscillators, individually responsive to the rising and setting sun, as a flexible solution to the challenge of behavioral and physiological adaptation to the changing seasons. The elegance and predictive power of this postulation has stimulated laboratories around the world in searches to identify and localize such hypothesized evening and morning oscillators, or sets of oscillators, in insects, rodents, and humans, with experimental designs and approaches keeping pace over the years with technological advances in biology and neuroscience. Here, we recount the conceptual origin and highlight the subsequent evolution of this dual oscillator model for the circadian clock in the mammalian suprachiasmatic nucleus; and how, despite our increasingly sophisticated view of this multicellular pacemaker, Pittendrigh's binary conception has remained influential in our clock models and metaphors.
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Affiliation(s)
- Jennifer A Evans
- Department of Biomedical Sciences, College of Health Sciences, Marquette University, Milwaukee, WI, USA.
| | - William J Schwartz
- Department of Neurology, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
- Groningen Institute for Evolutionary Life Sciences, Faculty of Science and Engineering, University of Groningen, Groningen, The Netherlands
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3
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Xie P, Xie X, Ye C, Dean KM, Laothamatas I, Taufique SKT, Takahashi J, Yamazaki S, Xu Y, Liu Y. Mammalian circadian clock proteins form dynamic interacting microbodies distinct from phase separation. Proc Natl Acad Sci U S A 2023; 120:e2318274120. [PMID: 38127982 PMCID: PMC10756265 DOI: 10.1073/pnas.2318274120] [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: 10/28/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) underlies diverse biological processes. Because most LLPS studies were performed in vitro using recombinant proteins or in cells that overexpress protein, the physiological relevance of LLPS for endogenous protein is often unclear. PERIOD, the intrinsically disordered domain-rich proteins, are central mammalian circadian clock components and interact with other clock proteins in the core circadian negative feedback loop. Different core clock proteins were previously shown to form large complexes. Circadian clock studies often rely on experiments that overexpress clock proteins. Here, we show that when Per2 transgene was stably expressed in cells, PER2 protein formed nuclear phosphorylation-dependent slow-moving LLPS condensates that recruited other clock proteins. Super-resolution microscopy of endogenous PER2, however, revealed formation of circadian-controlled, rapidly diffusing nuclear microbodies that were resistant to protein concentration changes, hexanediol treatment, and loss of phosphorylation, indicating that they are distinct from the LLPS condensates caused by protein overexpression. Surprisingly, only a small fraction of endogenous PER2 microbodies transiently interact with endogenous BMAL1 and CRY1, a conclusion that was confirmed in cells and in mice tissues, suggesting an enzyme-like mechanism in the circadian negative feedback process. Together, these results demonstrate that the dynamic interactions of core clock proteins are a key feature of mammalian circadian clock mechanism and the importance of examining endogenous proteins in LLPS and circadian clock studies.
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Affiliation(s)
- Pancheng Xie
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Cambridge-Su Genomic Resource Center, Soochow University, Suzhou, Jiangsu215123, China
| | - Xiaowen Xie
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Congrong Ye
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Kevin M. Dean
- Lyda Hill Department of Bioinformatics and Cecil H. and Ida Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Isara Laothamatas
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
| | - S. K. Tahajjul Taufique
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
| | - Joseph Takahashi
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
| | - Shin Yamazaki
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
| | - Ying Xu
- Cambridge-Su Genomic Resource Center, Soochow University, Suzhou, Jiangsu215123, China
| | - Yi Liu
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX75390
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4
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Xie P, Xie X, Ye C, Dean KM, Laothamatas I, Taufique SKT, Takahashi J, Yamazaki S, Xu Y, Liu Y. Mammalian circadian clock proteins form dynamic interacting microbodies distinct from phase separation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.19.563153. [PMID: 37961341 PMCID: PMC10634710 DOI: 10.1101/2023.10.19.563153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Liquid-liquid phase separation (LLPS) underlies diverse biological processes. Because most LLPS studies were performed in vitro or in cells that overexpress protein, the physiological relevance of LLPS is unclear. PERIOD proteins are central mammalian circadian clock components and interact with other clock proteins in the core circadian negative feedback loop. Different core clock proteins were previously shown to form large complexes. Here we show that when transgene was stably expressed, PER2 formed nuclear phosphorylation-dependent LLPS condensates that recruited other clock proteins. Super-resolution microscopy of endogenous PER2, however, revealed formation of circadian-controlled, rapidly diffusing microbodies that were resistant to protein concentration changes, hexanediol treatment, and loss of phosphorylation, indicating that they are distinct from the LLPS condensates caused by overexpression. Surprisingly, only a small fraction of endogenous PER2 microbodies transiently interact with endogenous BMAL1 and CRY1, a conclusion that was confirmed in cells and in mice tissues, suggesting an enzyme-like mechanism in the circadian negative feedback process. Together, these results demonstrate that the dynamic interactions of core clock proteins is a key feature of mammalian circadian clock mechanism and the importance of examining endogenous proteins in LLPS and circadian studies.
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Affiliation(s)
- Pancheng Xie
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Cambridge-Su Genomic Resource Center, Soochow University; Suzhou, Jiangsu 215123, China
| | - Xiaowen Xie
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Congrong Ye
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kevin M. Dean
- Lyda Hill Department of Bioinformatics and Cecil H. and Ida Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Isara Laothamatas
- Department of Neuroscience and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9111, USA
| | - S K Tahajjul Taufique
- Department of Neuroscience and Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9111, USA
| | - Joseph Takahashi
- Department of Neuroscience and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9111, USA
| | - Shin Yamazaki
- Department of Neuroscience and Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9111, USA
| | - Ying Xu
- Cambridge-Su Genomic Resource Center, Soochow University; Suzhou, Jiangsu 215123, China
| | - Yi Liu
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Laothamatas I, Rasmussen ES, Green CB, Takahashi JS. Metabolic and chemical architecture of the mammalian circadian clock. Cell Chem Biol 2023; 30:1033-1052. [PMID: 37708890 PMCID: PMC10631358 DOI: 10.1016/j.chembiol.2023.08.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 07/20/2023] [Accepted: 08/23/2023] [Indexed: 09/16/2023]
Abstract
Circadian rhythms are endogenous periodic biological processes that occur on a daily timescale. These rhythms are generated by a transcriptional/translational feedback loop that consists of the CLOCK-BMAL1 heterodimeric transcriptional activator complex and the PER1/2-CRY1/2-CK1δ/ε repressive complex. The output pathways of this molecular feedback loop generate circadian rhythmicity in various biological processes. Among these, metabolism is a primary regulatory target of the circadian clock which can also feedback to modulate clock function. This intertwined relationship between circadian rhythms and metabolism makes circadian clock components promising therapeutic targets. Despite this, pharmacological therapeutics that target the circadian clock are relatively rare. In this review, we hope to stimulate interest in chemical chronobiology by providing a comprehensive background on the molecular mechanism of mammalian circadian rhythms and their connection to metabolism, highlighting important studies in the chemical approach to circadian research, and offering our perspectives on future developments in the field.
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Affiliation(s)
- Isara Laothamatas
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Emil Sjulstok Rasmussen
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Carla B Green
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Joseph S Takahashi
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Schirmer AE, Kumar V, Schook A, Song EJ, Marshall MS, Takahashi JS. Cry1 expression during postnatal development is critical for the establishment of normal circadian period. Front Neurosci 2023; 17:1166137. [PMID: 37389366 PMCID: PMC10300422 DOI: 10.3389/fnins.2023.1166137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 05/23/2023] [Indexed: 07/01/2023] Open
Abstract
The mammalian circadian system generates an approximate 24-h rhythm through a complex autoregulatory feedback loop. Four genes, Period1 (Per1), Period2 (Per2), Cryptochrome1 (Cry1), and Cryptochrome2 (Cry2), regulate the negative feedback within this loop. Although these proteins have distinct roles within the core circadian mechanism, their individual functions are poorly understood. Here, we used a tetracycline trans-activator system (tTA) to examine the role of transcriptional oscillations in Cry1 and Cry2 in the persistence of circadian activity rhythms. We demonstrate that rhythmic Cry1 expression is an important regulator of circadian period. We then define a critical period from birth to postnatal day 45 (PN45) where the level of Cry1 expression is critical for setting the endogenous free running period in the adult animal. Moreover, we show that, although rhythmic Cry1 expression is important, in animals with disrupted circadian rhythms overexpression of Cry1 is sufficient to restore normal behavioral periodicity. These findings provide new insights into the roles of the Cryptochrome proteins in circadian rhythmicity and further our understanding of the mammalian circadian clock.
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Affiliation(s)
- Aaron E. Schirmer
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
- Department of Biology, Northeastern Illinois University, Chicago, IL, United States
| | - Vivek Kumar
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
- The Jackson Laboratory, Bar Harbor, ME, United States
| | - Andrew Schook
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
| | - Eun Joo Song
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
| | - Michael S. Marshall
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
- Department of Pathology, Massachusetts General Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
| | - Joseph S. Takahashi
- Department of Neurobiology, Northwestern University, Evanston, IL, United States
- Department of Neuroscience, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States
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Patton AP, Morris EL, McManus D, Wang H, Li Y, Chin JW, Hastings MH. Astrocytic control of extracellular GABA drives circadian timekeeping in the suprachiasmatic nucleus. Proc Natl Acad Sci U S A 2023; 120:e2301330120. [PMID: 37186824 PMCID: PMC10214171 DOI: 10.1073/pnas.2301330120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 04/12/2023] [Indexed: 05/17/2023] Open
Abstract
The hypothalamic suprachiasmatic nucleus (SCN) is the master mammalian circadian clock. Its cell-autonomous timing mechanism, a transcriptional/translational feedback loop (TTFL), drives daily peaks of neuronal electrical activity, which in turn control circadian behavior. Intercellular signals, mediated by neuropeptides, synchronize and amplify TTFL and electrical rhythms across the circuit. SCN neurons are GABAergic, but the role of GABA in circuit-level timekeeping is unclear. How can a GABAergic circuit sustain circadian cycles of electrical activity, when such increased neuronal firing should become inhibitory to the network? To explore this paradox, we show that SCN slices expressing the GABA sensor iGABASnFR demonstrate a circadian oscillation of extracellular GABA ([GABA]e) that, counterintuitively, runs in antiphase to neuronal activity, with a prolonged peak in circadian night and a pronounced trough in circadian day. Resolving this unexpected relationship, we found that [GABA]e is regulated by GABA transporters (GATs), with uptake peaking during circadian day, hence the daytime trough and nighttime peak. This uptake is mediated by the astrocytically expressed transporter GAT3 (Slc6a11), expression of which is circadian-regulated, being elevated in daytime. Clearance of [GABA]e in circadian day facilitates neuronal firing and is necessary for circadian release of the neuropeptide vasoactive intestinal peptide, a critical regulator of TTFL and circuit-level rhythmicity. Finally, we show that genetic complementation of the astrocytic TTFL alone, in otherwise clockless SCN, is sufficient to drive [GABA]e rhythms and control network timekeeping. Thus, astrocytic clocks maintain the SCN circadian clockwork by temporally controlling GABAergic inhibition of SCN neurons.
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Affiliation(s)
- Andrew P. Patton
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Emma L. Morris
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - David McManus
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Huan Wang
- State Key Laboratory of Membrane Biology, Peking University, School of Life Sciences, 100871Beijing, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University, School of Life Sciences, 100871Beijing, China
| | - Jason W. Chin
- PNAC Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Michael H. Hastings
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
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