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dos Santos Á, Fili N, Hari-Gupta Y, Gough RE, Wang L, Martin-Fernandez M, Aaron J, Wait E, Chew TL, Toseland CP. Binding partners regulate unfolding of myosin VI to activate the molecular motor. Biochem J 2022; 479:1409-1428. [PMID: 35722941 PMCID: PMC9342898 DOI: 10.1042/bcj20220025] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 06/15/2022] [Accepted: 06/20/2022] [Indexed: 11/22/2022]
Abstract
Myosin VI is the only minus-end actin motor and it is coupled to various cellular processes ranging from endocytosis to transcription. This multi-potent nature is achieved through alternative isoform splicing and interactions with a network of binding partners. There is a complex interplay between isoforms and binding partners to regulate myosin VI. Here, we have compared the regulation of two myosin VI splice isoforms by two different binding partners. By combining biochemical and single-molecule approaches, we propose that myosin VI regulation follows a generic mechanism, independently of the spliced isoform and the binding partner involved. We describe how myosin VI adopts an autoinhibited backfolded state which is released by binding partners. This unfolding activates the motor, enhances actin binding and can subsequently trigger dimerization. We have further expanded our study by using single-molecule imaging to investigate the impact of binding partners upon myosin VI molecular organization and dynamics.
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Affiliation(s)
- Ália dos Santos
- Department of Oncology and Metabolism, University of Sheffield, Sheffield S10 2RX, U.K
| | - Natalia Fili
- Department of Oncology and Metabolism, University of Sheffield, Sheffield S10 2RX, U.K
| | - Yukti Hari-Gupta
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, U.K
| | - Rosemarie E. Gough
- Department of Oncology and Metabolism, University of Sheffield, Sheffield S10 2RX, U.K
| | - Lin Wang
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford OX11 0QX, U.K
| | - Marisa Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford OX11 0QX, U.K
| | - Jesse Aaron
- Advanced Imaging Center, HHMI Janelia Research Campus, Ashburn, U.S.A
| | - Eric Wait
- Advanced Imaging Center, HHMI Janelia Research Campus, Ashburn, U.S.A
| | - Teng-Leong Chew
- Advanced Imaging Center, HHMI Janelia Research Campus, Ashburn, U.S.A
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2
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Hari-Gupta Y, Fili N, dos Santos Á, Cook AW, Gough RE, Reed HCW, Wang L, Aaron J, Venit T, Wait E, Grosse-Berkenbusch A, Gebhardt JCM, Percipalle P, Chew TL, Martin-Fernandez M, Toseland CP. Myosin VI regulates the spatial organisation of mammalian transcription initiation. Nat Commun 2022; 13:1346. [PMID: 35292632 PMCID: PMC8924246 DOI: 10.1038/s41467-022-28962-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/21/2022] [Indexed: 12/19/2022] Open
Abstract
During transcription, RNA Polymerase II (RNAPII) is spatially organised within the nucleus into clusters that correlate with transcription activity. While this is a hallmark of genome regulation in mammalian cells, the mechanisms concerning the assembly, organisation and stability remain unknown. Here, we have used combination of single molecule imaging and genomic approaches to explore the role of nuclear myosin VI (MVI) in the nanoscale organisation of RNAPII. We reveal that MVI in the nucleus acts as the molecular anchor that holds RNAPII in high density clusters. Perturbation of MVI leads to the disruption of RNAPII localisation, chromatin organisation and subsequently a decrease in gene expression. Overall, we uncover the fundamental role of MVI in the spatial regulation of gene expression.
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Affiliation(s)
- Yukti Hari-Gupta
- grid.9759.20000 0001 2232 2818School of Biosciences, University of Kent, Canterbury, UK ,grid.83440.3b0000000121901201Present Address: MRC LMCB, University College London, London, UK
| | - Natalia Fili
- grid.11835.3e0000 0004 1936 9262Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK ,grid.36511.300000 0004 0420 4262Present Address: School of Life Sciences, University of Lincoln, Lincoln, UK
| | - Ália dos Santos
- grid.11835.3e0000 0004 1936 9262Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Alexander W. Cook
- grid.11835.3e0000 0004 1936 9262Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Rosemarie E. Gough
- grid.11835.3e0000 0004 1936 9262Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Hannah C. W. Reed
- grid.9759.20000 0001 2232 2818School of Biosciences, University of Kent, Canterbury, UK
| | - Lin Wang
- grid.76978.370000 0001 2296 6998Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, UK
| | - Jesse Aaron
- grid.443970.dAdvanced Imaging Center, HHMI Janelia Research Campus, Ashburn, VA USA
| | - Tomas Venit
- grid.440573.10000 0004 1755 5934Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates
| | - Eric Wait
- grid.443970.dAdvanced Imaging Center, HHMI Janelia Research Campus, Ashburn, VA USA
| | | | | | - Piergiorgio Percipalle
- grid.440573.10000 0004 1755 5934Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates ,grid.10548.380000 0004 1936 9377Department of Molecular Bioscience, The Wenner Gren Institute, Stockholm University, Stockholm, SE Sweden
| | - Teng-Leong Chew
- grid.443970.dAdvanced Imaging Center, HHMI Janelia Research Campus, Ashburn, VA USA
| | - Marisa Martin-Fernandez
- grid.76978.370000 0001 2296 6998Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, UK
| | - Christopher P. Toseland
- grid.11835.3e0000 0004 1936 9262Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
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3
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Gupta CM, Ambaru B, Bajaj R. Emerging Functions of Actins and Actin Binding Proteins in Trypanosomatids. Front Cell Dev Biol 2020; 8:587685. [PMID: 33163497 PMCID: PMC7581878 DOI: 10.3389/fcell.2020.587685] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 09/22/2020] [Indexed: 01/20/2023] Open
Abstract
Actin is the major protein constituent of the cytoskeleton that performs wide range of cellular functions. It exists in monomeric and filamentous forms, dynamics of which is regulated by a large repertoire of actin binding proteins. However, not much was known about existence of these proteins in trypanosomatids, till the genome sequence data of three important organisms of this class, viz. Trypanosoma brucei, Trypanosoma cruzi and Leishmania major, became available. Here, we have reviewed most of the findings reported to date on the intracellular distribution, structure and functions of these proteins and based on them, we have hypothesized some of their functions. The major findings are as follows: (1) All the three organisms encode at least a set of ten actin binding proteins (profilin, twinfilin, ADF/cofilin, CAP/srv2, CAPz, coronin, two myosins, two formins) and one isoform of actin, except that T. cruzi encodes for three formins and several myosins along with four actins. (2) Actin 1 and a few actin binding proteins (ADF/cofilin, profilin, twinfilin, coronin and myosin13 in L. donovani; ADF/cofilin, profilin and myosin1 in T. brucei; profilin and myosin-F in T.cruzi) have been identified and characterized. (3) In all the three organisms, actin cytoskeleton has been shown to regulate endocytosis and intracellular trafficking. (4) Leishmania actin1 has been the most characterized protein among trypanosomatid actins. (5) This protein is localized to the cytoplasm as well as in the flagellum, nucleus and kinetoplast, and in vitro, it binds to DNA and displays scDNA relaxing and kDNA nicking activities. (6) The pure protein prefers to form bundles instead of thin filaments, and does not bind DNase1 or phalloidin. (7) Myosin13, myosin1 and myosin-F regulate endocytosis and intracellular trafficking, respectively, in Leishmania, T. brucei and T. cruzi. (8) Actin-dependent myosin13 motor is involved in dynamics and assembly of Leishmania flagellum. (9) Leishmania twinfilin localizes mostly to the nucleolus and coordinates karyokinesis by effecting splindle elongation and DNA synthesis. (10) Leishmania coronin binds and promotes actin filament formation and exists in tetrameric form rather than trimeric form, like other coronins. (11) Trypanosomatid profilins are essential for survival of all the three parasites.
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Affiliation(s)
- Chhitar M Gupta
- Institute of Bioinformatics and Applied Biotechnology, Bengaluru, India
| | - Bindu Ambaru
- Institute of Bioinformatics and Applied Biotechnology, Bengaluru, India.,Manipal Academy of Higher Education, Manipal, India
| | - Rani Bajaj
- Institute of Bioinformatics and Applied Biotechnology, Bengaluru, India.,Manipal Academy of Higher Education, Manipal, India
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4
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Bajaj R, Ambaru B, Gupta CM. Deciphering the role of UBA-like domains in intraflagellar distribution and functions of myosin XXI in Leishmania. PLoS One 2020; 15:e0232116. [PMID: 32343719 PMCID: PMC7188243 DOI: 10.1371/journal.pone.0232116] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/07/2020] [Indexed: 11/19/2022] Open
Abstract
Myosin XXI (Myo21) is a novel class of myosin present in all kinetoplastid parasites, such as Trypanosoma and Leishmania. This protein in Leishmania promastigotes is predominantly localized to the proximal region of the flagellum, and is involved in the flagellum assembly, cell motility and intracellular vesicle transport. As Myo21 contains two ubiquitin associated (UBA)-like domains (UBLD) in its amino acid sequence, we considered it of interest to analyze the role of these domains in the intracellular distribution and functions of this protein in Leishmania cells. In this context, we created green fluorescent protein (GFP)-conjugates of Myo21 constructs lacking one of the two UBLDs at a time or both the UBLDs as well as GFP-conjugates of only the two UBLDs and Myo21 tail lacking the two UBLDs and separately expressed them in the Leishmania cells. Our results show that unlike Myo21-GFP, Myo21-GFP constructs lacking either one or both the UBLDs failed to concentrate and co-distribute with actin in the proximal region of the flagellum. Nevertheless, the GFP conjugate of only the two UBLDs was found to predominantly localize to the flagellum base. Additionally, the cells that expressed only one or both the UBLDs-deleted Myo21-GFP constructs possessed shorter flagellum and displayed slower motility, compared to Myo21-GFP expressing cells. Further, the intracellular vesicle transport and cell growth were severely impaired in the cells that expressed both the UBLDs deleted Myo21-GFP construct, but in contrast, virtually no effect was observed on the intracellular vesicle transport and growth in the cells that expressed single UBLD deleted mutant proteins. Moreover, the observed slower growth of both the UBLDs-deleted Myo21-GFP expressing cells was primarily due to delayed G2/M phase caused by aberrant nuclear and daughter cell segregation during their cell division process. These results taken together clearly reveal that the presence of UBLDs in Myo21 are essentially required for its predominant localization to the flagellum base, and perhaps also in its involvement in the flagellum assembly and cell division. Possible role of UBLDs in involvement of Myo21 during Leishmania flagellum assembly and cell cycle is discussed.
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Affiliation(s)
- Rani Bajaj
- Institute of Bioinformatics & Applied Biotechnology, Bengaluru, Karnataka, India
- Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Bindu Ambaru
- Institute of Bioinformatics & Applied Biotechnology, Bengaluru, Karnataka, India
- Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Chhitar M. Gupta
- Institute of Bioinformatics & Applied Biotechnology, Bengaluru, Karnataka, India
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5
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Vizcaíno-Castillo A, Osorio-Méndez JF, Ambrosio JR, Hernández R, Cevallos AM. The complexity and diversity of the actin cytoskeleton of trypanosomatids. Mol Biochem Parasitol 2020; 237:111278. [PMID: 32353561 DOI: 10.1016/j.molbiopara.2020.111278] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 03/24/2020] [Accepted: 04/07/2020] [Indexed: 10/24/2022]
Abstract
Trypanosomatids are a monophyletic group of parasitic flagellated protists belonging to the order Kinetoplastida. Their cytoskeleton is primarily made up of microtubules in which no actin microfilaments have been detected. Although all these parasites contain actin, it is widely thought that their actin cytoskeleton is reduced when compared to most eukaryotic organisms. However, there is increasing evidence that it is more complex than previously thought. As in other eukaryotic organisms, trypanosomatids encode for a conventional actin that is expected to form microfilament-like structures, and for members of three conserved actin-related proteins probably involved in microfilament nucleation (ARP2, ARP3) and in gene expression regulation (ARP6). In addition to these canonical proteins, also encode for an expanded set of actins and actin-like proteins that seem to be restricted to kinetoplastids. Analysis of their amino acid sequences demonstrated that, although very diverse in primary sequence when compared to actins of model organisms, modelling of their tertiary structure predicted the presence of the actin fold in all of them. Experimental characterization has been done for only a few of the trypanosomatid actins and actin-binding proteins. The most studied is the conventional actin of Leishmania donovani (LdAct), which unusually requires both ATP and Mg2+ for polymerization, unlike other conventional actins that do not require ATP. Additionally, polymerized LdAct tends to assemble in bundles rather than in single filaments. Regulation of actin polymerization depends on their interaction with actin-binding proteins. In trypanosomatids, there is a reduced but sufficient core of actin-binding proteins to promote microfilament nucleation, turnover and stabilization. There are also genes encoding for members of two families of myosin motor proteins, including one lineage-specific. Homologues to all identified actin-family proteins and actin-binding proteins of trypanosomatids are also present in Paratrypanosoma confusum (an early branching trypanosomatid) and in Bodo saltans (a closely related free-living organism belonging to the trypanosomatid sister order of Bodonida) suggesting they were all present in their common ancestor. Secondary losses of these genes may have occurred during speciation within the trypanosomatids, with salivarian trypanosomes having lost many of them and stercorarian trypanosomes retaining most.
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Affiliation(s)
- Andrea Vizcaíno-Castillo
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, Coyoacán, 04510, Ciudad de México, Mexico
| | - Juan Felipe Osorio-Méndez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, Coyoacán, 04510, Ciudad de México, Mexico; Laboratorio de Microbiología y Biología Molecular, Programa de Medicina, Corporación Universitaria Empresarial Alexander von Humboldt, Armenia, Colombia
| | - Javier R Ambrosio
- Departamento de Microbiología y Parasitología de la Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal, 4510, D.F., Mexico
| | - Roberto Hernández
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, Coyoacán, 04510, Ciudad de México, Mexico
| | - Ana María Cevallos
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, Coyoacán, 04510, Ciudad de México, Mexico.
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6
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Trivedi DV, Nag S, Spudich A, Ruppel KM, Spudich JA. The Myosin Family of Mechanoenzymes: From Mechanisms to Therapeutic Approaches. Annu Rev Biochem 2020; 89:667-693. [PMID: 32169021 DOI: 10.1146/annurev-biochem-011520-105234] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Myosins are among the most fascinating enzymes in biology. As extremely allosteric chemomechanical molecular machines, myosins are involved in myriad pivotal cellular functions and are frequently sites of mutations leading to disease phenotypes. Human β-cardiac myosin has proved to be an excellent target for small-molecule therapeutics for heart muscle diseases, and, as we describe here, other myosin family members are likely to be potentially unique targets for treating other diseases as well. The first part of this review focuses on how myosins convert the chemical energy of ATP hydrolysis into mechanical movement, followed by a description of existing therapeutic approaches to target human β-cardiac myosin. The next section focuses on the possibility of targeting nonmuscle members of the human myosin family for several diseases. We end the review by describing the roles of myosin in parasites and the therapeutic potential of targeting them to block parasitic invasion of their hosts.
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Affiliation(s)
- Darshan V Trivedi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA; , , .,Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Suman Nag
- MyoKardia Inc., Brisbane, California 94005, USA;
| | - Annamma Spudich
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560-097, India;
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA; , , .,Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, USA.,Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305, USA
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA; , , .,Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, USA
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7
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de Souza DAS, Pavoni DP, Krieger MA, Ludwig A. Evolutionary analyses of myosin genes in trypanosomatids show a history of expansion, secondary losses and neofunctionalization. Sci Rep 2018; 8:1376. [PMID: 29358582 PMCID: PMC5778035 DOI: 10.1038/s41598-017-18865-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/18/2017] [Indexed: 11/09/2022] Open
Abstract
Myosins are motor proteins that comprise a large and diversified family important for a broad range of functions. Two myosin classes, I and XIII, were previously assigned in Trypanosomatids, based mainly on the studies of Trypanosoma cruzi, T. brucei and Leishmania major, and important human pathogenic species; seven orphan myosins were identified in T. cruzi. Our results show that the great variety of T. cruzi myosins is also present in some closely related species and in Bodo saltans, a member of an early divergent branch of Kinetoplastida. Therefore, these myosins should no longer be considered "orphans". We proposed the classification of a kinetoplastid-specific myosin group into a new class, XXXVI. Moreover, our phylogenetic data suggest that a great repertoire of myosin genes was present in the last common ancestor of trypanosomatids and B. saltans, mainly resulting from several gene duplications. These genes have since been predominantly maintained in synteny in some species, and secondary losses explain the current distribution. We also found two interesting genes that were clearly derived from myosin genes, demonstrating that possible redundant or useless genes, instead of simply being lost, can serve as raw material for the evolution of new genes and functions.
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Affiliation(s)
- Denise Andréa Silva de Souza
- Laboratório de Genômica Funcional, Instituto Carlos Chagas- ICC/Fiocruz-, PR, Curitiba, 81350-010, Brazil.,Programa de Pós-graduação em Biociências e Biotecnologia - ICC/Fiocruz-, PR, Curitiba, 81350-010, Brazil
| | - Daniela Parada Pavoni
- Laboratório de Genômica Funcional, Instituto Carlos Chagas- ICC/Fiocruz-, PR, Curitiba, 81350-010, Brazil.,Programa de Pós-graduação em Biociências e Biotecnologia - ICC/Fiocruz-, PR, Curitiba, 81350-010, Brazil
| | - Marco Aurélio Krieger
- Laboratório de Genômica Funcional, Instituto Carlos Chagas- ICC/Fiocruz-, PR, Curitiba, 81350-010, Brazil. .,Programa de Pós-graduação em Biociências e Biotecnologia - ICC/Fiocruz-, PR, Curitiba, 81350-010, Brazil. .,Instituto de Biologia Molecular do Paraná, Curitiba, 81350-010, Brazil.
| | - Adriana Ludwig
- Laboratório de Genômica Funcional, Instituto Carlos Chagas- ICC/Fiocruz-, PR, Curitiba, 81350-010, Brazil. .,Instituto de Biologia Molecular do Paraná, Curitiba, 81350-010, Brazil.
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8
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Self-organization of actin networks by a monomeric myosin. Proc Natl Acad Sci U S A 2016; 113:E8387-E8395. [PMID: 27956608 DOI: 10.1073/pnas.1612719113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The organization of actomyosin networks lies at the center of many types of cellular motility, including cell polarization and collective cell migration during development and morphogenesis. Myosin-IXa is critically involved in these processes. Using total internal reflection fluorescence microscopy, we resolved actin bundles assembled by myosin-IXa. Electron microscopic data revealed that the bundles consisted of highly ordered lattices with parallel actin polarity. The myosin-IXa motor domains aligned across the network, forming cross-links at a repeat distance of precisely 36 nm, matching the helical repeat of actin. Single-particle image processing resolved three distinct conformations of myosin-IXa in the absence of nucleotide. Using cross-correlation of a modeled actomyosin crystal structure, we identified sites of additional mass, which can only be accounted for by the large insert in loop 2 exclusively found in the motor domain of class IX myosins. We show that the large insert in loop 2 binds calmodulin and creates two coordinated actin-binding sites that constrain the actomyosin interactions generating the actin lattices. The actin lattices introduce orientated tracks at specific sites in the cell, which might install platforms allowing Rho-GTPase-activating protein (RhoGAP) activity to be focused at a definite locus. In addition, the lattices might introduce a myosin-related, force-sensing mechanism into the cytoskeleton in cell polarization and collective cell migration.
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9
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Batters C, Veigel C. Mechanics and Activation of Unconventional Myosins. Traffic 2016; 17:860-71. [PMID: 27061900 DOI: 10.1111/tra.12400] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/07/2016] [Accepted: 03/07/2016] [Indexed: 12/01/2022]
Abstract
Many types of cellular motility are based on the myosin family of motor proteins ranging from muscle contraction to exo- and endocytosis, cytokinesis, cell locomotion or signal transduction in hearing. At the center of this wide range of motile processes lies the adaptation of the myosins for each specific mechanical task and the ability to coordinate the timing of motor protein mobilization and targeting. In recent years, great progress has been made in developing single molecule technology to characterize the diverse mechanical properties of the unconventional myosins. Here, we discuss the basic mechanisms and mechanical adaptations of unconventional myosins, and emerging principles regulating motor mobilization and targeting.
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Affiliation(s)
- Christopher Batters
- Department of Cellular Physiology, Ludwig-Maximilians-Universität München, Schillerstrasse 44, 80336, Munich, Germany.,Center for Nanosciences (CeNS) München, 80799, Munich, Germany
| | - Claudia Veigel
- Department of Cellular Physiology, Ludwig-Maximilians-Universität München, Schillerstrasse 44, 80336, Munich, Germany.,Center for Nanosciences (CeNS) München, 80799, Munich, Germany
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10
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Abstract
The ability to coordinate the timing of motor protein activation lies at the center of a wide range of cellular motile processes including endocytosis, cell division, and cancer cell migration. We show that calcium dramatically alters the conformation and activity of the myosin-VI motor implicated in pivotal steps of these processes. We resolved the change in motor conformation and in structural flexibility using single particle analysis of electron microscopic data and identified interacting domains using fluorescence spectroscopy. We discovered that calcium binding to calmodulin increases the binding affinity by a factor of 2,500 for a bipartite binding site on myosin-VI. The ability of calcium-calmodulin to seek out and bridge between binding site components directs a major rearrangement of the motor from a compact dormant state into a cargo binding primed state that is nonmotile. The lack of motility at high calcium is due to calmodulin switching to a higher affinity binding site, which leaves the original IQ-motif exposed, thereby destabilizing the lever arm. The return to low calcium can either restabilize the lever arm, required for translocating the cargo-bound motors toward the center of the cell, or refold the cargo-free motors into an inactive state ready for the next cellular calcium flux.
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11
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Unconventional actins and actin-binding proteins in human protozoan parasites. Int J Parasitol 2015; 45:435-47. [DOI: 10.1016/j.ijpara.2015.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/19/2014] [Accepted: 01/27/2015] [Indexed: 12/11/2022]
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12
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Docampo R, Huang G. Calcium signaling in trypanosomatid parasites. Cell Calcium 2014; 57:194-202. [PMID: 25468729 DOI: 10.1016/j.ceca.2014.10.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/27/2014] [Accepted: 10/29/2014] [Indexed: 11/29/2022]
Abstract
Calcium ion (Ca(2+)) is an important second messenger in trypanosomatids and essential for their survival although prolonged high intracellular Ca(2+) levels lead to cell death. As other eukaryotic cells, trypanosomes use two sources of Ca(2+) for generating signals: Ca(2+) release from intracellular stores and Ca(2+) entry across the plasma membrane. Ca(2+) release from intracellular stores is controlled by the inositol 1,4,5-trisphosphate receptor (IP3R) that is located in acidocalcisomes, acidic organelles that are the primary Ca(2+) reservoir in these cells. A plasma membrane Ca(2+)-ATPase controls the cytosolic Ca(2+) levels and a number of pumps and exchangers are responsible for Ca(2+) uptake and release from intracellular compartments. The trypanosomatid genomes contain a wide variety of signaling and regulatory proteins that bind Ca(2+) as well as many Ca(2+)-binding proteins that await further characterization. The mitochondrial Ca(2+) transporters of trypanosomatids have an important role in the regulation of cell bioenergetics and flagellar Ca(2+) appears to have roles in sensing the environment. In trypanosomatids in which an intracellular life cycle is present, Ca(2+) signaling is important for host cell invasion.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30620, USA; Departamento de Patologia Clínica, State University of Campinas, Campinas, SP 13083, Brazil.
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30620, USA
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13
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Toseland CP. Fluorescence to study the ATPase mechanism of motor proteins. ACTA ACUST UNITED AC 2014; 105:67-86. [PMID: 25095991 DOI: 10.1007/978-3-0348-0856-9_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This chapter provides an overview of different methodologies to dissect the ATPase mechanism of motor proteins. The use of ATP is fundamental to how these molecular engines work and how they can use the energy to perform various cellular roles. Rapid reaction and single-molecule techniques will be discussed to monitor reactions in real time through the application of fluorescence intensity, anisotropy and FRET. These approaches utilise fluorescent nucleotides and biosensors. While not every technique may be suitable for your motor protein, the different ways to determine the ATPase mechanism should allow a good evaluation of the kinetic parameters.
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Affiliation(s)
- Christopher P Toseland
- Chromosome Organisation and Dynamics, Max-Planck Institute of Biochemistry, Martinsried, 82152, Germany,
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Rodrigues JCF, Godinho JLP, de Souza W. Biology of human pathogenic trypanosomatids: epidemiology, lifecycle and ultrastructure. Subcell Biochem 2014; 74:1-42. [PMID: 24264239 DOI: 10.1007/978-94-007-7305-9_1] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Leishmania and Trypanosoma belong to the Trypanosomatidae family and cause important human infections such as leishmaniasis, Chagas disease, and sleeping sickness. Leishmaniasis, caused by protozoa belonging to Leishmania, affects about 12 million people worldwide and can present different clinical manifestations, i.e., visceral leishmaniasis (VL), cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), diffuse cutaneous leishmaniasis (DCL), and post-kala-azar dermal leishmaniasis (PKDL). Chagas disease, also known as American trypanosomiasis, is caused by Trypanosoma cruzi and is mainly prevalent in Latin America but is increasingly occurring in the United States, Canada, and Europe. Sleeping sickness or human African trypanosomiasis (HAT), caused by two sub-species of Trypanosoma brucei (i.e., T. b. rhodesiense and T. b. gambiense), occurs only in sub-Saharan Africa countries. These pathogenic trypanosomatids alternate between invertebrate and vertebrate hosts throughout their lifecycles, and different developmental stages can live inside the host cells and circulate in the bloodstream or in the insect gut. Trypanosomatids have a classical eukaryotic ultrastructural organization with some of the same main organelles found in mammalian host cells, while also containing special structures and organelles that are absent in other eukaryotic organisms. For example, the mitochondrion is ramified and contains a region known as the kinetoplast, which houses the mitochondrial DNA. Also, the glycosomes are specialized peroxisomes containing glycolytic pathway enzymes. Moreover, a layer of subpellicular microtubules confers mechanic rigidity to the cell. Some of these structures have been investigated to determine their function and identify potential enzymes and metabolic pathways that may constitute targets for new chemotherapeutic drugs.
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Affiliation(s)
- Juliany Cola Fernandes Rodrigues
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil,
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Calmodulin regulates dimerization, motility, and lipid binding of Leishmania myosin XXI. Proc Natl Acad Sci U S A 2013; 111:E227-36. [PMID: 24379364 DOI: 10.1073/pnas.1319285110] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Myosin XXI is the only myosin expressed in Leishmania parasites. Although it is assumed that it performs a variety of motile functions, the motor's oligomerization states, cargo-binding, and motility are unknown. Here we show that binding of a single calmodulin causes the motor to adopt a monomeric state and to move actin filaments. In the absence of calmodulin, nonmotile dimers that cross-linked actin filaments were formed. Unexpectedly, structural analysis revealed that the dimerization domains include the calmodulin-binding neck region, essential for the generation of force and movement in myosins. Furthermore, monomeric myosin XXI bound to mixed liposomes, whereas the dimers did not. Lipid-binding sections overlapped with the dimerization domains, but also included a phox-homology domain in the converter region. We propose a mechanism of myosin regulation where dimerization, motility, and lipid binding are regulated by calmodulin. Although myosin-XXI dimers might act as nonmotile actin cross-linkers, the calmodulin-binding monomers might transport lipid cargo in the parasite.
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