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Ng HY, Adly AN, Whelpley DH, Suhandynata RT, Zhou H, Morgan DO. Phosphate-binding pocket on cyclin B governs CDK substrate phosphorylation and mitotic timing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582599. [PMID: 38464173 PMCID: PMC10925351 DOI: 10.1101/2024.02.28.582599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Cell cycle progression is governed by complexes of the cyclin-dependent kinases (CDKs) and their regulatory subunits cyclin and Cks1. CDKs phosphorylate hundreds of substrates, often at multiple sites. Multisite phosphorylation depends on Cks1, which binds initial priming phosphorylation sites to promote secondary phosphorylation at other sites. Here, we describe a similar role for a recently discovered phosphate-binding pocket (PP) on B-type cyclins. Mutation of the PP in Clb2, the major mitotic cyclin of budding yeast, alters bud morphology and delays the onset of anaphase. Using phosphoproteomics in vivo and kinase reactions in vitro, we find that mutation of the PP reduces phosphorylation of several CDK substrates, including the Bud6 subunit of the polarisome and the Cdc16 and Cdc27 subunits of the anaphase-promoting complex/cyclosome. We conclude that the cyclin PP, like Cks1, controls the timing of multisite phosphorylation on CDK substrates, thereby helping to establish the robust timing of cell-cycle events.
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Affiliation(s)
- Henry Y. Ng
- Department of Physiology, University of California San Francisco, San Francisco CA
| | - Armin N. Adly
- Department of Physiology, University of California San Francisco, San Francisco CA
| | - Devon H. Whelpley
- Department of Physiology, University of California San Francisco, San Francisco CA
| | - Raymond T. Suhandynata
- School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla CA
- Department of Pathology, University of California San Diego, La Jolla CA
| | - Huilin Zhou
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla CA
| | - David O. Morgan
- Department of Physiology, University of California San Francisco, San Francisco CA
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Descriptive and functional analyses of four cyclin proteins in Trichomonas vaginalis. Mol Biochem Parasitol 2022; 252:111528. [PMID: 36273631 DOI: 10.1016/j.molbiopara.2022.111528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 10/05/2022] [Accepted: 10/18/2022] [Indexed: 12/31/2022]
Abstract
Trichomonas vaginalis is an early divergent protozoan parasite that causes trichomoniasis, the most common non-viral sexually transmitted infection. In metazoans, there is abundant and detailed research on the cell cycle and the components involved in the regulation mechanisms. Regulators such as the cyclin-dependent kinases (CDKs) and cyclins activate the highly regulated processes of cell division. While CDKs have important roles in the phosphorylation of specific substrates, cyclins are important activating-components of CDKs that allow orderly passage through the different stages of the cell cycle. Cell cycle cyclins are characterized by showing drastic changes in their concentration during the cell cycle progression. However, in protists such as T. vaginalis, some biological processes such as cell cycle regulation remain less well studied. In an attempt to gain insight into cell cycle regulation in T. vaginalis, as an initial approach we characterized four proteins with features of cyclins. The genes encoding these putative cyclins were cloned to produce the recombinant proteins TvCYC1, TvCYC2, TvCYC3, and TvCYC4. The functional activity of TvCYC2, TvCYC3, and TvCYC4 was assessed through their complementation of a yeast cln1,2,3Δ mutant strain; TvCYC1 was not able to complement this mutant. Furthermore, our results suggest that TvCYC1, TvCYC2, and TvCYC3, are able to interact with and activate the kinase activity of TvCRK1, a kinase previously characterized by our group. The present study represents the first characterization of cyclins potentially involved in cell cycle regulation in T. vaginalis.
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Multisite phosphorylation by Cdk1 initiates delayed negative feedback to control mitotic transcription. Curr Biol 2022; 32:256-263.e4. [PMID: 34818519 PMCID: PMC8752490 DOI: 10.1016/j.cub.2021.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 08/02/2021] [Accepted: 11/01/2021] [Indexed: 01/12/2023]
Abstract
Cell-cycle progression is driven by the phosphorylation of cyclin-dependent kinase (Cdk) substrates.1-3 The order of substrate phosphorylation depends in part on the general rise in Cdk activity during the cell cycle,4-7 together with variations in substrate docking to sites on associated cyclin and Cks subunits.3,6,8-10 Many substrates are modified at multiple sites to provide more complex regulation.10-14 Here, we describe an elegant regulatory circuit based on multisite phosphorylation of Ndd1, a transcriptional co-activator of budding yeast genes required for mitotic progression.11,12 As cells enter mitosis, Ndd1 phosphorylation by Cdk1 is known to promote mitotic cyclin (CLB2) gene transcription, resulting in positive feedback.13-16 Consistent with these findings, we show that low Cdk1 activity promotes CLB2 expression at mitotic entry. We also find, however, that when high Cdk1 activity accumulates in a mitotic arrest, CLB2 expression is inhibited. Inhibition is accompanied by Ndd1 degradation, and we present evidence that degradation is triggered by multisite Ndd1 phosphorylation by high mitotic Cdk1-Clb2 activity. Complete Ndd1 phosphorylation by Clb2-Cdk1-Cks1 requires the phosphothreonine-binding site of Cks1, as well as a recently identified phosphate-binding pocket on the cyclin Clb2.17 We therefore propose that initial phosphorylation by Cdk1 primes Ndd1 for delayed secondary phosphorylation at suboptimal sites that promote degradation. Together, our results suggest that rising levels of mitotic Cdk1 activity act at multiple phosphorylation sites on Ndd1, first triggering rapid positive feedback and then promoting delayed negative feedback, resulting in a pulse of mitotic gene expression.
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Yu J, Raia P, Ghent CM, Raisch T, Sadian Y, Cavadini S, Sabale PM, Barford D, Raunser S, Morgan DO, Boland A. Structural basis of human separase regulation by securin and CDK1-cyclin B1. Nature 2021; 596:138-142. [PMID: 34290405 PMCID: PMC8482764 DOI: 10.1038/s41586-021-03764-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 06/23/2021] [Indexed: 02/06/2023]
Abstract
In early mitosis, the duplicated chromosomes are held together by the ring-shaped cohesin complex1. Separation of chromosomes during anaphase is triggered by separase-a large cysteine endopeptidase that cleaves the cohesin subunit SCC1 (also known as RAD212-4). Separase is activated by degradation of its inhibitors, securin5 and cyclin B6, but the molecular mechanisms of separase regulation are not clear. Here we used cryogenic electron microscopy to determine the structures of human separase in complex with either securin or CDK1-cyclin B1-CKS1. In both complexes, separase is inhibited by pseudosubstrate motifs that block substrate binding at the catalytic site and at nearby docking sites. As in Caenorhabditis elegans7 and yeast8, human securin contains its own pseudosubstrate motifs. By contrast, CDK1-cyclin B1 inhibits separase by deploying pseudosubstrate motifs from intrinsically disordered loops in separase itself. One autoinhibitory loop is oriented by CDK1-cyclin B1 to block the catalytic sites of both separase and CDK19,10. Another autoinhibitory loop blocks substrate docking in a cleft adjacent to the separase catalytic site. A third separase loop contains a phosphoserine6 that promotes complex assembly by binding to a conserved phosphate-binding pocket in cyclin B1. Our study reveals the diverse array of mechanisms by which securin and CDK1-cyclin B1 bind and inhibit separase, providing the molecular basis for the robust control of chromosome segregation.
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Affiliation(s)
- Jun Yu
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Pierre Raia
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Chloe M Ghent
- Department of Physiology, University of California, San Francisco, San Francisco, CA, USA
| | - Tobias Raisch
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Yashar Sadian
- Bioimaging Center, University of Geneva, Geneva, Switzerland
| | - Simone Cavadini
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Pramod M Sabale
- Department of Organic Chemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | | | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - David O Morgan
- Department of Physiology, University of California, San Francisco, San Francisco, CA, USA
| | - Andreas Boland
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland.
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Jiang SW, Zhou W, Wang J, Little LM, Leaphart L, Jay J, Igbinigie E, Chen H, Li J. Gene expression patterns associated with human placental trophoblast differentiation. Clin Chim Acta 2019; 495:637-645. [PMID: 29329728 DOI: 10.1016/j.cca.2018.01.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 01/08/2018] [Indexed: 02/04/2023]
Abstract
Cell fusion is a hallmark of placental trophoblast cell differentiation and the mature syncytiotrophoblasts play essential roles for fetal-maternal exchange and production of pregnancy-related hormones. Using a well-established in vitro trophoblast differentiation model, we performed a microarray analysis on mRNA expression in trophoblast and syncytiotrophoblast cell cultures. Dramatic changes in gene expression patterns were detected during trophoblast differentiation. Real-time PCR analysis confirmed the reliability of the microarray data. As many as 3524 novel and known genes have been found to be up- or down-regulated for >2-fold. A number of cell cycle regulator including CDC6, CDC20, Cyclins B2, L1 and E2, were down-regulated in the syncytiotrophoblast, providing a mechanism for the loss of mitotic activity during trophoblast differentiation. Further characterization on the identified genes may lead to better understanding of placental patho-physiology in obstetric diseases such as preeclampsia.
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Affiliation(s)
- Shi-Wen Jiang
- Department of Obstetrics and Gynecology, the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, China; Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA 31404, USA; Department of Obstetrics and Gynecology, Memorial Health Hospital, Mercer University School of Medicine, Savannah, GA 31404, USA
| | - Wei Zhou
- Department of Obstetrics, Chongqing Health Center for Women and Children, Chongqing 400013, China
| | - Jianhao Wang
- School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu 213000, China
| | - Lauren M Little
- Department of Obstetrics and Gynecology, Memorial Health Hospital, Mercer University School of Medicine, Savannah, GA 31404, USA
| | - Lynn Leaphart
- Department of Obstetrics and Gynecology, Memorial Health Hospital, Mercer University School of Medicine, Savannah, GA 31404, USA
| | - Jacob Jay
- Mercer University School of Medicine, Savannah, GA 31404, USA
| | - Eseosaserea Igbinigie
- Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA 31404, USA
| | - Haibin Chen
- Department of Histology & Embryology, Shantou University Medical College, Shantou, Guangdong 515041, China.
| | - Jinping Li
- Department of Obstetrics and Gynecology, the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, China; Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA 31404, USA; Department of Obstetrics and Gynecology, Memorial Health Hospital, Mercer University School of Medicine, Savannah, GA 31404, USA; School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu 213000, China.
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