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Ultrastructural immunogold localization of major sperm protein (MSP) in spermatogenic cells of the nematode Acrobeles complexus (Nematoda, Rhabditida). Micron 2016; 89:43-55. [DOI: 10.1016/j.micron.2016.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/14/2016] [Accepted: 07/14/2016] [Indexed: 01/07/2023]
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Roberts TM, Stewart M. Role of Major Sperm Protein (MSP) in the Protrusion and Retraction of Ascaris Sperm. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 297:265-93. [DOI: 10.1016/b978-0-12-394308-8.00007-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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3
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del Castillo-Olivares A, Smith HE. Critical contact residues that mediate polymerization of nematode major sperm protein. J Cell Biochem 2008; 104:477-87. [PMID: 18022815 DOI: 10.1002/jcb.21636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The polymerization of protein filaments provides the motive force in a variety of cellular processes involving cell motility and intracellular transport. Regulated assembly and disassembly of the major sperm protein (MSP) underlies amoeboid movement in nematode sperm, and offers an attractive model system for characterizing the biomechanical properties of filament formation and force generation. To that end, structure-function studies of MSP from the nematode Caenorhabditis elegans have been performed. Recombinant MSP was purified from Escherichia coli using a novel affinity chromatography technique, and filament assembly was assessed by in vitro polymerization in the presence of polyethylene glycol. Prior molecular studies and structure from X-ray crystallography have implicated specific residues in protein-protein interactions necessary for filament assembly. Purified MSP containing substitutions in these residues fails to form filaments in vitro. Short peptides based on predicted sites of interaction also effectively disrupt MSP polymerization. These results confirm the structural determination of intermolecular contacts and demonstrate the importance of these residues in MSP assembly.
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Affiliation(s)
- Antonio del Castillo-Olivares
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA
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Lev S, Ben Halevy D, Peretti D, Dahan N. The VAP protein family: from cellular functions to motor neuron disease. Trends Cell Biol 2008; 18:282-90. [PMID: 18468439 DOI: 10.1016/j.tcb.2008.03.006] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 03/24/2008] [Accepted: 03/31/2008] [Indexed: 01/10/2023]
Abstract
The VAMP-associated proteins (VAPs) are highly conserved integral endoplasmic reticulum membrane proteins implicated in diverse cellular functions, including the regulation of lipid transport and homeostasis, membrane trafficking, neurotransmitter release, stabilization of presynaptic microtubules, and the unfolded protein response. Recently, a single missense mutation within the human VAP-B gene was identified in three forms of familial motor neuron disease. In this review, we integrate results from studies of yeast, fly and mammalian VAPs that provide insight into the structural features of these proteins, the network of VAP-interacting proteins, their possible physiological functions, and their involvement in motor neuron disease.
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Affiliation(s)
- Sima Lev
- The Molecular Cell Biology Department, Weizmann Institute of Science, Rehovot 76100, Israel.
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5
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Abstract
Nematode sperm provide a simple and specialized system for studying the molecular mechanism of amoeboid cell motility. Locomotion is generated by the assembly dynamics of their cytoskeleton, which is based on the major sperm protein (MSP). Protrusive force is generated at the leading edge of the lamellipod by MSP filament formation and bundling, whereas the contractile force that drags the rearward cell body forward is generated by cytoskeleton disassembly. The dynamics of the system can be reconstituted in vitro using cell-free extracts of Ascaris sperm, in which vesicles derived from the leading edge of the cell can be either pushed or pulled. The addition of ATP to the cell-free extract initiates MSP filament polymerization and bundling immediately behind the vesicle, and the expansion of the resulting gel pushes the vesicle at rates comparable to those seen in living cells. In contrast, the addition of Yersinia tyrosine phosphatase generates depolymerization and gel contraction that pulls the vesicles. Overall, nematode sperm motility illustrates that cell locomotion can be generated by cytoskeletal dynamics alone without the use of myosin-like motor proteins.
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Affiliation(s)
- Murray Stewart
- MRC Laboratory of Molecular Biology, Hills Rd, Cambridge CB2 2QH, England
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Grant RP, Buttery SM, Ekman GC, Roberts TM, Stewart M. Structure of MFP2 and its function in enhancing MSP polymerization in Ascaris sperm amoeboid motility. J Mol Biol 2005; 347:583-95. [PMID: 15755452 DOI: 10.1016/j.jmb.2005.01.054] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Revised: 01/20/2005] [Accepted: 01/20/2005] [Indexed: 11/19/2022]
Abstract
The simplicity and specialization of the cell motility machinery of Ascaris sperm provides a powerful system in which to probe the basic molecular mechanism of amoeboid cell motility. Although Ascaris sperm locomotion closely resembles that seen in many other types of crawling cell, movement is generated by modulation of a cytoskeleton based on the major sperm protein (MSP) rather than the actin present in other cell types. The Ascaris motility machinery can be studied conveniently in a cell-free in vitro system based on the movement of plasma membrane vesicles by fibres constructed from bundles of MSP filaments. In addition to ATP, MSP and a plasma membrane protein, reconstitution of MSP motility in this cell-free extract requires cytosolic proteins to orchestrate the site-specific assembly and bundling of MSP filaments that generates locomotion. One of these proteins, MFP2, accelerates the rate of movement in this assay. Here, we describe crystal structures of two isoforms of MFP2 and show that both are constructed from two domains that have the same fold based on a novel, compact beta sheet arrangement. Patterns of conservation observed in a structure-based analysis of MFP2 sequences from different nematode species identified regions that may be putative functional interfaces involved both in interactions between MFP2 domains and also with other components of the sperm motility machinery. Analysis of the growth of fibres in vitro in the presence of added MFP2 indicated that MFP2 increases the rate of locomotion by enhancing the effective rate of MSP filament polymerization. This observation, together with the structural data, suggests that MFP2 may function in a manner analogous to formins in actin-based motility.
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Affiliation(s)
- Richard P Grant
- MRC Laboratory of Molecular Biology, Hills Rd., Cambridge CB2 2QH, UK
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Baker AME, Roberts TM, Stewart M. 2.6 A resolution crystal structure of helices of the motile major sperm protein (MSP) of Caenorhabditis elegans. J Mol Biol 2002; 319:491-9. [PMID: 12051923 DOI: 10.1016/s0022-2836(02)00294-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The amoeboid locomotion of nematode sperm is mediated by the assembly dynamics of the major sperm protein (MSP). MSP forms fibrous networks based on a hierarchy of macromolecular assemblies: helical subfilaments are built from MSP dimers; filaments are formed from two subfilaments coiling round one another; and filaments themselves supercoil to produce bundles. To provide a structural context for understanding the role of these macromolecular assemblies in cell locomotion, we have determined the 2.6 A resolution structure of crystals of Caenorhabditis elegans MSP that are constructed from helices of MSP chains that are analogous to the subfilaments from which filaments are constructed. Comparison with the crystal structures of dimers and helical assemblies of Ascaris suum MSP has identified five conserved interaction interfaces that suggest how subfilaments interact in filaments and how filaments can form bundles. The interfaces frequently involve the loop containing residues 78-85, which is divergent between MSP homologues, and the loop containing residues 98-103, which is highly conserved.
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Affiliation(s)
- Anne M E Baker
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
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Abstract
Sperm of the nematode, Ascaris suum, crawl using lamellipodial protrusion, adhesion and retraction, a process analogous to the amoeboid motility of other eukaryotic cells. However, rather than employing an actin cytoskeleton to generate locomotion, nematode sperm use the major sperm protein (MSP). Moreover, nematode sperm lack detectable molecular motors or the battery of actin-binding proteins that characterize actin-based motility. The Ascaris system provides a simple ‘stripped down’ version of a crawling cell in which to examine the basic mechanism of cell locomotion independently of other cellular functions that involve the cytoskeleton. Here we present a mechanochemical analysis of crawling in Ascaris sperm. We construct a finite element model wherein (a) localized filament polymerization and bundling generate the force for lamellipodial extension and (b) energy stored in the gel formed from the filament bundles at the leading edge is subsequently used to produce the contraction that pulls the rear of the cell forward. The model reproduces the major features of crawling sperm and provides a framework in which amoeboid cell motility can be analyzed. Although the model refers primarily to the locomotion of nematode sperm, it has important implications for the mechanics of actin-based cell motility.Movies available on-line.
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Affiliation(s)
- Dean Bottino
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720-3112, USA
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Italiano JE, Stewart M, Roberts TM. How the assembly dynamics of the nematode major sperm protein generate amoeboid cell motility. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 202:1-34. [PMID: 11061562 DOI: 10.1016/s0074-7696(01)02002-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Nematode sperm are amoeboid cells that use a major sperm protein (MSP) cytoskeleton in place of a conventional actin cytoskeleton to power their amoeboid motility. In these simple, specialized cells cytoskeletal dynamics is tightly coupled to locomotion. Studies have capitalized on this feature to explore the key structural properties of MSP and to reconstitute motility both in vivo and in vitro. This review discusses how the mechanistic properties shared by the MSP machinery and actin-based motility systems lead to a "push-pull" mechanism for amoeboid cell motility in which cytoskeletal assembly and disassembly at opposite ends of the lamellipodium are associated with independent forces for protrusion of the leading edge and retraction of the cell body.
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Affiliation(s)
- J E Italiano
- Department of Biological Science, Florida State University, Tallahassee 32306, USA
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Abstract
Not all biological movements are caused by molecular motors sliding along filaments or tubules. Just as springs and ratchets can store or release energy and rectify motion in physical systems, their analogs can perform similar functions in biological systems. The energy of biological springs is derived from hydrolysis of a nucleotide or the binding of a ligand, whereas biological ratchets are powered by Brownian movements of polymerizing filaments. However, the viscous and fluctuating cellular environment and the mechanochemistry of soft biological systems constrain the modes of motion generated and the mechanisms for energy storage, control, and release.
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Affiliation(s)
- L Mahadevan
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
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Roberts TM, Stewart M. Acting like actin. The dynamics of the nematode major sperm protein (msp) cytoskeleton indicate a push-pull mechanism for amoeboid cell motility. J Cell Biol 2000; 149:7-12. [PMID: 10747081 PMCID: PMC2175093 DOI: 10.1083/jcb.149.1.7] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- T M Roberts
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA.
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Haaf A, LeClaire L, Roberts G, Kent HM, Roberts TM, Stewart M, Neuhaus D. Solution structure of the motile major sperm protein (MSP) of Ascaris suum - evidence for two manganese binding sites and the possible role of divalent cations in filament formation. J Mol Biol 1998; 284:1611-24. [PMID: 9878374 DOI: 10.1006/jmbi.1998.2291] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The major sperm protein (MSP) of Ascaris suum mediates amoeboid motility by forming an extensive intermeshed system of cytoskeletal filaments analogous to that formed by actin in many other amoeboid cells. MSP is a dimeric molecule that polymerizes to form non-polar filaments constructed from two helical subfilaments that wind round one another. Moreover, MSP filaments can interact with one another to form higher-order assemblies without requiring the range of accessory proteins usually employed in actin-based systems. A knowledge of how MSP polymerizes and forms the hierarchical series of helical MSP macromolecular assemblies is fundamental to understanding locomotion in these cells. Here we describe the solution structure of MSP dimers determined by NMR spectroscopy under conditions where MSP does not polymerize to form filaments. The solution structure is indistinguishable from that observed in putative MSP subfilament helices by X-ray crystallography, indicating that MSP polymerization is not accompanied by a major conformational change. We also show that the rate of MSP polymerization associated with movement of vesicles in an in vitro motility assay is enhanced by the presence of magnesium and manganese ions and use NMR to show that the primary residues that bind these ions are 24-25 and 83-86. These residues are distant from the interface formed between MSP dimers in subfilament helices, and so are probably not involved in this level of polymerization. Instead the manganese and magnesium ion binding appears to be associated with the assembly of subfilaments into filaments and their subsequent aggregation into bundles.
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Affiliation(s)
- A Haaf
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK
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Smith HE, Ward S. Identification of protein-protein interactions of the major sperm protein (MSP) of Caenorhabditis elegans. J Mol Biol 1998; 279:605-19. [PMID: 9641981 DOI: 10.1006/jmbi.1998.1793] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In nematodes, sperm are amoeboid cells that crawl via an extended pseudopod. Unlike those in other crawling cells, this pseudopod contains little or no actin; instead, it utilizes the major sperm protein (MSP). In vivo and in vitro studies of Ascaris suum MSP have demonstrated that motility occurs via the regulated assembly and disassembly of MSP filaments. Filaments composed of MSP dimers are thought to provide the motive force. We have employed the yeast two-hybrid system to investigate MSP-MSP interactions and provide insights into the process of MSP filament formation. Fusions of the Caenorhabditis elegans msp-142 gene to both the lexA DNA binding domain (LEXA-MSP) and a transcriptional activation domain (AD-MSP) interact to drive expression of a lacZ reporter construct. A library of AD-MSP mutants was generated via mutagenic PCR and screened for clones that fail to interact with LEXA-MSP. Single missense mutations were identified and mapped to the crystal structure of A. suum MSP. Two classes of mutations predicted from the structure were recovered: changes in residues critical for the overall fold of the protein, and changes in residues in the dimerization interface. Multiple additional mutations were obtained in the two carboxy-terminal beta strands, a region not predicted to be involved in protein folding or dimer formation. Size fractionation of bacterially expressed MSPs indicates that mutations in this region do not abolish dimer formation. A number of compensating mutations that restore the interaction also map to this region. The data suggest that the carboxy-terminal beta strands are directly involved in interactions required for MSP filament assembly.
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Affiliation(s)
- H E Smith
- Department of Molecular and Cellular Biology, University of Arizona, Tucson 85721, USA
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Bullock TL, McCoy AJ, Kent HM, Roberts TM, Stewart M. Structural basis for amoeboid motility in nematode sperm. NATURE STRUCTURAL BIOLOGY 1998; 5:184-9. [PMID: 9501910 DOI: 10.1038/nsb0398-184] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cell locomotion in amoeboid nematode sperm is generated by the vectorial assembly and bundling of filaments of the major sperm protein (MSP). MSP filaments are constructed from two helical subfilaments and here we describe the structure of putative MSP subfilament helices determined by X-ray crystallography at 3.3 A resolution. In addition to establishing the interfaces involved in polymerization, this structural model shows that the MSP helices are constructed from dimers and have no overall polarity, suggesting that it is unlikely that molecular motors play a direct role in the generation of protrusive force in these amoeboid cells.
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Affiliation(s)
- T L Bullock
- MRC Laboratory of Molecular Biology, Cambridge, UK
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Abstract
Parasitic nematode infections remain a major public health problem in many parts of the world. Because most of the current strategies aimed at controlling parasitic nematode infections have met with only limited success, it may be time to consider alternative approaches. An aspect of nematode biology that has drawn little attention as a target for control is the reproductive process. Although there are numerous facets of the overall reproductive biology of nematodes that hold potential as targets for intervention, Alan Scott here focuses on the male reproductive system, and outlines some of the known unique processes and characteristics of sperm formation and sperm function that could be exploited to block fertilization.
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Affiliation(s)
- A L Scott
- Department of Molecular Microbiology and Immunology, School of Hygiene and Public Health, The Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205-2179, USA. ascott@
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Mansir A, Justine JL. Actin and major sperm protein in spermatids and spermatozoa of the parasitic nematode Heligmosomoides polygyrus. Mol Reprod Dev 1996; 45:332-41. [PMID: 8916044 DOI: 10.1002/(sici)1098-2795(199611)45:3<332::aid-mrd10>3.0.co;2-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Nematode spermatozoa are amoeboid cells. In Caenorhabditis elegans and Ascaris suum, previous studies have reported that sperm motility does not involve actin, but, instead, requires a specific cytoskeletal protein, namely major-sperm-protein (MSP). In Heligmosomoides polygyrus, a species with large and elongate spermatids and spermatozoa, cell organelles are easily identified even with light microscopy. Electrophoresis of Heligmosomoides sperm proteins indicates that the main protein band has a molecular weight of about 15 kDa, as MSP in other nematodes, and is specifically labelled by an anti-MSP antibody raised against C. elegans MSP. A minor band at 43 kDa was specifically labelled by an anti-actin antibody. Reaction of anti-actin and anti-MSP antibodies is specific to, and restricted to, their respective targets. Actin and MSP localisation, studied by indirect immunofluorescence in male germ cells of Heligmosomoides polygyrus, are similar: spermatids show rows of dots, corresponding to the fibrous bodies, around an unlabelled central longitudinal core; spermatozoa are labelled strictly in an anterior crescent-shaped cap, at the opposite pole to the nucleus, which contains fibres of the MSP cytoskeleton. Phalloidin labelling shows that F-actin is present in spermatids, but absent in spermatozoa. Tropomyosin shows a distinct pattern in spermatids, but is located in the MSP and actin-containing cap in spermatozoa. It is hypothesized that actin plays a role in the shaping of the cell and in the arrangement of its organelles during nematode spermiogenesis, when MSP is present, in an inactive state, in the fibrous bodies. The concentration of actin and tropomyosin in the anterior cap is not compatible with previous theories about the MSP cytoskeleton, which is supposed to act in the absence of actin.
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Affiliation(s)
- A Mansir
- Laboratoire de Biologie parasitaire-Protistologie-Helminthologie, Muséum national d'histoire naturelle, Paris, France
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Italiano JE, Roberts TM, Stewart M, Fontana CA. Reconstitution in vitro of the motile apparatus from the amoeboid sperm of Ascaris shows that filament assembly and bundling move membranes. Cell 1996; 84:105-14. [PMID: 8548814 DOI: 10.1016/s0092-8674(00)80997-6] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have developed an in vitro motility system from Ascaris sperm, unique amoeboid cells that use filament arrays composed of major sperm protein (MSP) instead of an actin-based apparatus for locomotion. Addition of ATP to sperm extracts induces formation of fibers approximately 2 microns in diameter. These fibers display the key features of the MSP cytoskeleton in vivo. Each fiber consists of a meshwork of MSP filaments and has at one end a vesicle derived from the plasma membrane at the leading edge of the cell. Fiber growth is due to filament assembly at the vesicle; thus, fiber elongation results in vesicle translocation. This in vitro system demonstrates directly that localized polymerization and bundling of filaments can move membranes and provides a powerful assay for evaluating the molecular mechanism of amoeboid cell motility.
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Affiliation(s)
- J E Italiano
- Department of Biological Science, Florida State University, Tallahassee 32306, USA
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Affiliation(s)
- J A Theriot
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
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Abstract
The simplicity and specialization of the amoeboid motility of nematode sperm can give intriguing insights into the molecular mechanisms underlying movement in more conventional actin-based systems. Amoeboid motility in nematode sperm is based on their major sperm protein. Advances over the past year in understanding the assembly of this protein in vivo and in vitro have underlined the importance of vectorial assembly and filament bundling. In this system, it is possible that these two properties may be sufficient to generate motility that closely resembles that seen in conventional actin-based systems.
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Affiliation(s)
- T M Roberts
- Department of Biological Science, Florida State University 32306, USA
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