51
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Winding M, Gelfand VI. Breaking up isn't easy: myosin V and its cargoes need Dma1 ubiquitin ligase's help. Dev Cell 2014; 28:479-80. [PMID: 24636254 DOI: 10.1016/j.devcel.2014.02.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In this issue of Developmental Cell, Yau et al. (2014) report that degradation of cargo adapters releases yeast vacuoles and peroxisomes from myosin V (Myo2) and terminates organelle transport from the mother cell to the bud.
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Affiliation(s)
- Michael Winding
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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52
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Yau RG, Peng Y, Valiathan RR, Birkeland SR, Wilson TE, Weisman LS. Release from myosin V via regulated recruitment of an E3 ubiquitin ligase controls organelle localization. Dev Cell 2014; 28:520-33. [PMID: 24636257 DOI: 10.1016/j.devcel.2014.02.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 09/13/2013] [Accepted: 02/03/2014] [Indexed: 10/25/2022]
Abstract
Molecular motors transport organelles to specific subcellular locations. Upon arrival at their correct locations, motors release organelles via unknown mechanisms. The yeast myosin V, Myo2, binds the vacuole-specific adaptor Vac17 to transport the vacuole from the mother cell to the bud. Here, we show that vacuole detachment from Myo2 occurs in multiple regulated steps along the entire pathway of vacuole transport. Detachment initiates in the mother cell with the phosphorylation of Vac17 that recruits the E3 ligase Dma1 to the vacuole. However, Dma1 recruitment also requires the assembly of the vacuole transport complex and is first observed after the vacuole enters the bud. Dma1 remains on the vacuole until the bud and mother vacuoles separate. Subsequently, Dma1 targets Vac17 for proteasomal degradation. Notably, we find that the termination of peroxisome transport also requires Dma1. We predict that this is a general mechanism that detaches myosin V from select cargoes.
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Affiliation(s)
- Richard G Yau
- Program in Cell and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Yutian Peng
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Shanda R Birkeland
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Thomas E Wilson
- Program in Cell and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Lois S Weisman
- Program in Cell and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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53
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Wang N, Lo Presti L, Zhu YH, Kang M, Wu Z, Martin SG, Wu JQ. The novel proteins Rng8 and Rng9 regulate the myosin-V Myo51 during fission yeast cytokinesis. ACTA ACUST UNITED AC 2014; 205:357-75. [PMID: 24798735 PMCID: PMC4018781 DOI: 10.1083/jcb.201308146] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The myosin-V family of molecular motors is known to be under sophisticated regulation, but our knowledge of the roles and regulation of myosin-Vs in cytokinesis is limited. Here, we report that the myosin-V Myo51 affects contractile ring assembly and stability during fission yeast cytokinesis, and is regulated by two novel coiled-coil proteins, Rng8 and Rng9. Both rng8Δ and rng9Δ cells display similar defects as myo51Δ in cytokinesis. Rng8 and Rng9 are required for Myo51's localizations to cytoplasmic puncta, actin cables, and the contractile ring. Myo51 puncta contain multiple Myo51 molecules and walk continuously on actin filaments in rng8(+) cells, whereas Myo51 forms speckles containing only one dimer and does not move efficiently on actin tracks in rng8Δ. Consistently, Myo51 transports artificial cargos efficiently in vivo, and this activity is regulated by Rng8. Purified Rng8 and Rng9 form stable higher-order complexes. Collectively, we propose that Rng8 and Rng9 form oligomers and cluster multiple Myo51 dimers to regulate Myo51 localization and functions.
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Affiliation(s)
- Ning Wang
- Department of Molecular Genetics, 2 Department of Molecular and Cellular Biochemistry, and 3 Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
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54
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Klecker T, Böckler S, Westermann B. Making connections: interorganelle contacts orchestrate mitochondrial behavior. Trends Cell Biol 2014; 24:537-45. [PMID: 24786308 DOI: 10.1016/j.tcb.2014.04.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 01/07/2023]
Abstract
Mitochondria are highly dynamic organelles. During their life cycle they frequently fuse and divide, and damaged mitochondria are removed by autophagic degradation. These processes serve to maintain mitochondrial function and ensure optimal energy supply for the cell. It has recently become clear that this complex mitochondrial behavior is governed to a large extent by interactions with other organelles. In this review, we describe mitochondrial contacts with the endoplasmic reticulum (ER), plasma membrane, and peroxisomes. In particular, we highlight how mitochondrial fission, distribution, inheritance, and turnover are orchestrated by interorganellar contacts in yeast and metazoa. These interactions are pivotal for the integration of the dynamic mitochondrial network into the architecture of eukaryotic cells.
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Affiliation(s)
- Till Klecker
- Institut für Zellbiologie, Universität Bayreuth, 95440 Bayreuth, Germany
| | - Stefan Böckler
- Institut für Zellbiologie, Universität Bayreuth, 95440 Bayreuth, Germany
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55
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Steffens A, Jaegle B, Tresch A, Hülskamp M, Jakoby M. Processing-body movement in Arabidopsis depends on an interaction between myosins and DECAPPING PROTEIN1. PLANT PHYSIOLOGY 2014; 164:1879-92. [PMID: 24525673 PMCID: PMC3982750 DOI: 10.1104/pp.113.233031] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Accepted: 02/12/2014] [Indexed: 05/18/2023]
Abstract
Processing (P)-bodies are cytoplasmic RNA protein aggregates responsible for the storage, degradation, and quality control of translationally repressed messenger RNAs in eukaryotic cells. In mammals, P-body-related RNA and protein exchanges are actomyosin dependent, whereas P-body movement requires intact microtubules. In contrast, in plants, P-body motility is actin based. In this study, we show the direct interaction of the P-body core component DECAPPING PROTEIN1 (DCP1) with the tails of different unconventional myosins in Arabidopsis (Arabidopsis thaliana). By performing coexpression studies with AtDCP1, dominant-negative myosin fragments, as well as functional full-length myosin XI-K, the association of P-bodies and myosins was analyzed in detail. Finally, the combination of mutant analyses and characterization of P-body movement patterns showed that myosin XI-K is essential for fast and directed P-body transport. Together, our data indicate that P-body movement in plants is governed by myosin XI members through direct binding to AtDCP1 rather than through an adapter protein, as known for membrane-coated organelles. Interspecies and intraspecies interaction approaches with mammalian and yeast protein homologs suggest that this mechanism is evolutionarily conserved among eukaryotes.
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56
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Colombi P, Webster BM, Fröhlich F, Lusk CP. The transmission of nuclear pore complexes to daughter cells requires a cytoplasmic pool of Nsp1. ACTA ACUST UNITED AC 2013; 203:215-32. [PMID: 24165936 PMCID: PMC3812967 DOI: 10.1083/jcb.201305115] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nuclear pore complexes (NPCs) are essential protein assemblies that span the nuclear envelope and establish nuclear-cytoplasmic compartmentalization. We have investigated mechanisms that control NPC number in mother and daughter cells during the asymmetric division of budding yeast. By simultaneously tracking existing NPCs and newly synthesized NPC protomers (nups) through anaphase, we uncovered a pool of the central channel nup Nsp1 that is actively targeted to the bud in association with endoplasmic reticulum. Bud targeting required an intact actin cytoskeleton and the class V myosin, Myo2. Selective inhibition of cytoplasmic Nsp1 or inactivation of Myo2 reduced the inheritance of NPCs in daughter cells, leading to a daughter-specific loss of viability. Our data are consistent with a model in which Nsp1 releases a barrier that otherwise prevents NPC passage through the bud neck. It further supports the finding that NPC inheritance, not de novo NPC assembly, is primarily responsible for controlling NPC number in daughter cells.
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Affiliation(s)
- Paolo Colombi
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
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57
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Nascimento AFZ, Trindade DM, Tonoli CCC, de Giuseppe PO, Assis LHP, Honorato RV, de Oliveira PSL, Mahajan P, Burgess-Brown NA, von Delft F, Larson RE, Murakami MT. Structural insights into functional overlapping and differentiation among myosin V motors. J Biol Chem 2013; 288:34131-34145. [PMID: 24097982 PMCID: PMC3837155 DOI: 10.1074/jbc.m113.507202] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/27/2013] [Indexed: 11/06/2022] Open
Abstract
Myosin V (MyoV) motors have been implicated in the intracellular transport of diverse cargoes including vesicles, organelles, RNA-protein complexes, and regulatory proteins. Here, we have solved the cargo-binding domain (CBD) structures of the three human MyoV paralogs (Va, Vb, and Vc), revealing subtle structural changes that drive functional differentiation and a novel redox mechanism controlling the CBD dimerization process, which is unique for the MyoVc subclass. Moreover, the cargo- and motor-binding sites were structurally assigned, indicating the conservation of residues involved in the recognition of adaptors for peroxisome transport and providing high resolution insights into motor domain inhibition by CBD. These results contribute to understanding the structural requirements for cargo transport, autoinhibition, and regulatory mechanisms in myosin V motors.
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Affiliation(s)
- Andrey F Z Nascimento
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, Campinas, São Paulo 13083-100, Brazil
| | - Daniel M Trindade
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, Campinas, São Paulo 13083-100, Brazil
| | - Celisa C C Tonoli
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, Campinas, São Paulo 13083-100, Brazil
| | - Priscila O de Giuseppe
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, Campinas, São Paulo 13083-100, Brazil
| | - Leandro H P Assis
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, Campinas, São Paulo 13083-100, Brazil
| | - Rodrigo V Honorato
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, Campinas, São Paulo 13083-100, Brazil
| | - Paulo S L de Oliveira
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, Campinas, São Paulo 13083-100, Brazil
| | - Pravin Mahajan
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | | | - Frank von Delft
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Roy E Larson
- Department of Cellular & Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, São Paulo 14049-900, Brazil
| | - Mario T Murakami
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, Campinas, São Paulo 13083-100, Brazil.
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58
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Westermann B. Mitochondrial inheritance in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:1039-46. [PMID: 24183694 DOI: 10.1016/j.bbabio.2013.10.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 10/08/2013] [Accepted: 10/22/2013] [Indexed: 11/25/2022]
Abstract
Mitochondria are the site of oxidative phosphorylation, play a key role in cellular energy metabolism, and are critical for cell survival and proliferation. The propagation of mitochondria during cell division depends on replication and partitioning of mitochondrial DNA, cytoskeleton-dependent mitochondrial transport, intracellular positioning of the organelle, and activities coordinating these processes. Budding yeast Saccharomyces cerevisiae has proven to be a valuable model organism to study the mechanisms that drive segregation of the mitochondrial genome and determine mitochondrial partitioning and behavior in an asymmetrically dividing cell. Here, I review past and recent advances that identified key components and cellular pathways contributing to mitochondrial inheritance in yeast. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira.
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59
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Wu M, Kalyanasundaram A, Zhu J. Structural and biomechanical basis of mitochondrial movement in eukaryotic cells. Int J Nanomedicine 2013; 8:4033-42. [PMID: 24187495 PMCID: PMC3810443 DOI: 10.2147/ijn.s52132] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Mitochondria serve as energy-producing organelles in eukaryotic cells. In addition to providing the energy supply for cells, the mitochondria are also involved in other processes, such as proliferation, differentiation, information transfer, and apoptosis, and play an important role in regulation of cell growth and the cell cycle. In order to achieve these functions, the mitochondria need to move to the corresponding location. Therefore, mitochondrial movement has a crucial role in normal physiologic activity, and any mitochondrial movement disorder will cause irreparable damage to the organism. For example, recent studies have shown that abnormal movement of the mitochondria is likely to be the reason for Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease, Parkinson's disease, and schizophrenia. So, in the cell, especially in the particular polarized cell, the appropriate distribution of mitochondria is crucial to the function and survival of the cell. Mitochondrial movement is mainly associated with the cytoskeleton and related proteins. However, those components play different roles according to cell type. In this paper, we summarize the structural basis of mitochondrial movement, including microtubules, actin filaments, motor proteins, and adaptin, and review studies of the biomechanical mechanisms of mitochondrial movement in different types of cells.
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Affiliation(s)
- Min Wu
- Laboratory of Biomechanics and Engineering, Institute of Biophysics, College of Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
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60
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Chernyakov I, Santiago-Tirado F, Bretscher A. Active segregation of yeast mitochondria by Myo2 is essential and mediated by Mmr1 and Ypt11. Curr Biol 2013; 23:1818-24. [PMID: 24012315 DOI: 10.1016/j.cub.2013.07.053] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/10/2013] [Accepted: 07/16/2013] [Indexed: 01/01/2023]
Abstract
Active segregation of essential organelles is required for successful cell division. The essential budding yeast myosin V Myo2 actively segregates most organelles along polarized actin cables. The mechanism of mitochondrial segregation remains controversial, with movement driven by actin polymerization, movement driven by association with transported cortical endoplasmic reticulum (ER), and direct transport by Myo2 proposed as models. Two nonessential proteins, Mmr1 and the Rab GTPase Ypt11, bind Myo2 and have been implicated in mitochondrial inheritance, although their specific roles are also contended. We generated myo2(sens) mutations that exhibit no overt phenotype but render MMR1 essential and have compromised Ypt11 binding. We then isolated myo2(sens)mmr1(ts) conditional mutants and determined that they have a specific and severe defect in active mitochondrial inheritance, revealing mitochondrial transport by Myo2 as an essential function. ypt11Δ mmr1(ts) cells also have conditional defects in growth and active transport of mitochondria into the bud, both of which are suppressed by artificially forcing mitochondrial inheritance. At the restrictive temperature, cells defective in mitochondrial inheritance give rise to dead buds that go through cytokinesis normally, showing no evidence of a proposed cell-cycle mitochondrial inheritance checkpoint. Thus, active mitochondrial inheritance is an essential process and a function of Myo2 that requires either Mmr1 or Ypt11.
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Affiliation(s)
- Irina Chernyakov
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Weill Hall, Cornell University, Ithaca, NY 14850, USA
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61
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Vevea JD, Swayne TC, Boldogh IR, Pon LA. Inheritance of the fittest mitochondria in yeast. Trends Cell Biol 2013; 24:53-60. [PMID: 23932848 DOI: 10.1016/j.tcb.2013.07.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/02/2013] [Accepted: 07/08/2013] [Indexed: 01/01/2023]
Abstract
Eukaryotic cells compartmentalize their biochemical processes within organelles, which have specific functions that must be maintained for overall cellular health. As the site of aerobic energy mobilization and essential biosynthetic activities, mitochondria are critical for cell survival and proliferation. Here, we describe mechanisms to control the quality and quantity of mitochondria within cells with an emphasis on findings from the budding yeast Saccharomyces cerevisiae. We also describe how mitochondrial quality and quantity control systems that operate during cell division affect lifespan and cell cycle progression.
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Affiliation(s)
- Jason D Vevea
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Theresa C Swayne
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Istvan R Boldogh
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA; Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.
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62
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Wei Z, Liu X, Yu C, Zhang M. Structural basis of cargo recognitions for class V myosins. Proc Natl Acad Sci U S A 2013. [PMID: 23798443 PMCID: PMC3710815 DOI: 10.1073/pnas.1306768110;] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
Abstract
Class V myosins (MyoV), the most studied unconventional myosins, recognize numerous cargos mainly via the motor's globular tail domain (GTD). Little is known regarding how MyoV-GTD recognizes such a diverse array of cargos specifically. Here, we solved the crystal structures of MyoVa-GTD in its apo-form and in complex with two distinct cargos, melanophilin and Rab interacting lysosomal protein-like 2. The apo-MyoVa-GTD structure indicates that most mutations found in patients with Griscelli syndrome, microvillus inclusion disease, or cancers or in "dilute" rodents likely impair the folding of GTD. The MyoVa-GTD/cargo complex structure reveals two distinct cargo-binding surfaces, one primarily via charge-charge interaction and the other mainly via hydrophobic interactions. Structural and biochemical analysis reveal the specific cargo-binding specificities of various isoforms of mammalian MyoV as well as very different cargo recognition mechanisms of MyoV between yeast and higher eukaryotes. The MyoVa-GTD structures resolved here provide a framework for future functional studies of vertebrate class V myosins.
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Affiliation(s)
- Zhiyi Wei
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, and
- Center of Systems Biology, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
- To whom correspondence may be addressed. E-mail: and
| | - Xiaotian Liu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, and
| | - Cong Yu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, and
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, and
- Center of Systems Biology, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
- To whom correspondence may be addressed. E-mail: and
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63
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Abstract
Class V myosins (MyoV), the most studied unconventional myosins, recognize numerous cargos mainly via the motor's globular tail domain (GTD). Little is known regarding how MyoV-GTD recognizes such a diverse array of cargos specifically. Here, we solved the crystal structures of MyoVa-GTD in its apo-form and in complex with two distinct cargos, melanophilin and Rab interacting lysosomal protein-like 2. The apo-MyoVa-GTD structure indicates that most mutations found in patients with Griscelli syndrome, microvillus inclusion disease, or cancers or in "dilute" rodents likely impair the folding of GTD. The MyoVa-GTD/cargo complex structure reveals two distinct cargo-binding surfaces, one primarily via charge-charge interaction and the other mainly via hydrophobic interactions. Structural and biochemical analysis reveal the specific cargo-binding specificities of various isoforms of mammalian MyoV as well as very different cargo recognition mechanisms of MyoV between yeast and higher eukaryotes. The MyoVa-GTD structures resolved here provide a framework for future functional studies of vertebrate class V myosins.
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64
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Myosin motors at neuronal synapses: drivers of membrane transport and actin dynamics. Nat Rev Neurosci 2013; 14:233-47. [DOI: 10.1038/nrn3445] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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65
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Lackner LL. Determining the shape and cellular distribution of mitochondria: the integration of multiple activities. Curr Opin Cell Biol 2013; 25:471-6. [PMID: 23490281 DOI: 10.1016/j.ceb.2013.02.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 02/13/2013] [Indexed: 12/28/2022]
Abstract
Both mitochondrial and cellular function are influenced by the overall structure and position of mitochondria within cells. Proper mitochondrial structure and position are achieved through the concerted actions of multiple activities. These include mitochondrial dynamics, motility and tethering. Mitochondrial dynamics and motility facilitate transport of the organelle, while tethering pathways serve to stably position mitochondria at specific cellular sites. Recent studies have advanced our understanding of the molecular mechanisms underlying the activities that shape and position the mitochondrial network and have identified the ER as an active participant in many of these activities.
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Affiliation(s)
- Laura L Lackner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
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66
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Lewandowska A, Macfarlane J, Shaw JM. Mitochondrial association, protein phosphorylation, and degradation regulate the availability of the active Rab GTPase Ypt11 for mitochondrial inheritance. Mol Biol Cell 2013; 24:1185-95. [PMID: 23427260 PMCID: PMC3623639 DOI: 10.1091/mbc.e12-12-0848] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
There are conflicting models regarding the role of the Ypt11 GTPase in mitochondrial inheritance during yeast budding. This study demonstrates that Ypt11 function requires mitochondrial membrane targeting and GTPase domain–dependent effector interactions. In addition, the abundance of active Ypt11 forms is controlled by phosphorylation and degradation. The Rab GTPase Ypt11 is a Myo2-binding protein implicated in mother-to-bud transport of the cortical endoplasmic reticulum (ER), late Golgi, and mitochondria during yeast division. However, its reported subcellular localization does not reflect all of these functions. Here we show that Ypt11 is normally a low-abundance protein whose ER localization is only detected when the protein is highly overexpressed. Although it has been suggested that ER-localized Ypt11 and ER–mitochondrial contact sites might mediate passive transport of mitochondria into the bud, we found that mitochondrial, but not ER, association is essential for Ypt11 function in mitochondrial inheritance. Our studies also reveal that Ypt11 function is regulated at multiple levels. In addition to membrane targeting and GTPase domain–dependent effector interactions, the abundance of active Ypt11 forms is controlled by phosphorylation status and degradation. We present a model that synthesizes these new features of Ypt11 function and regulation in mitochondrial inheritance.
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Affiliation(s)
- Agnieszka Lewandowska
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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67
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van Gisbergen PAC, Bezanilla M. Plant formins: membrane anchors for actin polymerization. Trends Cell Biol 2013; 23:227-33. [PMID: 23317636 DOI: 10.1016/j.tcb.2012.12.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/06/2012] [Accepted: 12/10/2012] [Indexed: 11/18/2022]
Abstract
In plants, the actin cytoskeleton plays a fundamental role in intracellular transport, cell growth, and morphology. Formins are central regulators of actin polymerization and actin-based processes in many eukaryotes. Plants have a diverse family of formins and this diversity arose early in land plant evolution, probably deriving from family expansion and domain acquisition. Recently, formins from different plant lineages have been studied and the focus of these studies is beginning to shift from biochemical characterization to in vivo function. In vivo studies have shown that distinct biochemical activities confer specific cellular functions. Despite these differences, many plant formins have in common a direct link to the plasma membrane, suggesting that formins in plants are important links between the plasma membrane and actin remodeling.
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68
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Bond LM, Tumbarello DA, Kendrick-Jones J, Buss F. Small-molecule inhibitors of myosin proteins. Future Med Chem 2013; 5:41-52. [PMID: 23256812 PMCID: PMC3971371 DOI: 10.4155/fmc.12.185] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Advances in screening and computational methods have enhanced recent efforts to discover/design small-molecule protein inhibitors. One attractive target for inhibition is the myosin family of motor proteins. Myosins function in a wide variety of cellular processes, from intracellular trafficking to cell motility, and are implicated in several human diseases (e.g., cancer, hypertrophic cardiomyopathy, deafness and many neurological disorders). Potent and selective myosin inhibitors are, therefore, not only a tool for understanding myosin function, but are also a resource for developing treatments for diseases involving myosin dysfunction or overactivity. This review will provide a brief overview of the characteristics and scientific/therapeutic applications of the presently identified small-molecule myosin inhibitors before discussing the future of myosin inhibitor and activator design.
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Affiliation(s)
- Lisa M Bond
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
| | - David A Tumbarello
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
| | | | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
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69
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Short B. Organelles compete for their inheritance. J Biophys Biochem Cytol 2012. [PMCID: PMC3392933 DOI: 10.1083/jcb.1981iti2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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