scholarly journals CryoEM structure of Drosophila flight muscle thick filaments at 7 Å resolution

2020 ◽  
Vol 3 (8) ◽  
pp. e202000823
Author(s):  
Nadia Daneshparvar ◽  
Dianne W Taylor ◽  
Thomas S O’Leary ◽  
Hamidreza Rahmani ◽  
Fatemeh Abbasiyeganeh ◽  
...  
Keyword(s):  
Striated Muscle ◽  
Flight Muscle ◽  
Myosin Ii ◽  
Coiled Coil ◽  
Fruit Fly ◽  
Actin Binding ◽  
Thick Filaments ◽  
Flight Muscles ◽  
Lethocerus Indicus ◽  
Globular Head

Striated muscle thick filaments are composed of myosin II and several non-myosin proteins. Myosin II’s long α-helical coiled-coil tail forms the dense protein backbone of filaments, whereas its N-terminal globular head containing the catalytic and actin-binding activities extends outward from the backbone. Here, we report the structure of thick filaments of the flight muscle of the fruit fly Drosophila melanogaster at 7 Å resolution. Its myosin tails are arranged in curved molecular crystalline layers identical to flight muscles of the giant water bug Lethocerus indicus. Four non-myosin densities are observed, three of which correspond to ones found in Lethocerus; one new density, possibly stretchin-mlck, is found on the backbone outer surface. Surprisingly, the myosin heads are disordered rather than ordered along the filament backbone. Our results show striking myosin tail similarity within flight muscle filaments of two insect orders separated by several hundred million years of evolution.

scholarly journals CryoEM Structure of Drosophila Flight Muscle Thick Filaments at 7Å Resolution

2020 ◽  
Author(s):  
Nadia Daneshparvar ◽  
Dianne W. Taylor ◽  
Thomas S. O’Leary ◽  
Hamidreza Rahmani ◽  
Fatemeh Abbasi Yeganeh ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Striated Muscle ◽  
Flight Muscle ◽  
Coiled Coil ◽  
Thick Filament ◽  
Fruit Fly ◽  
Actin Binding ◽  
Thick Filaments ◽  
Flight Muscles ◽  
Lethocerus Indicus

AbstractStriated muscle thick filaments are composed of myosin II and several non-myosin proteins. Myosin II’s long α-helical coiled-coil tail forms the dense protein backbone of filaments while its N-terminal globular head containing the catalytic and actin binding activities extends outward from the backbone. Here we report the structure of thick filaments of the flight muscle of the fruit fly Drosophila melanogaster at 7 Å resolution. Its myosin tails are arranged in curved molecular crystalline layers identical to flight muscles of the giant waterbug Lethocerus indicus. Four non-myosin densities are observed, three of which correspond to ones found in Lethocerus; one new density, possibly stretchin-Mlck, is found on the backbone outer surface. Surprisingly, the myosin heads are disordered rather than ordered along the filament backbone. Our results show striking myosin tail similarity within flight muscle filaments of two insect orders separated by several hundred million years of evolution.Significance StatementMyosin thick filaments are one of striated muscle’s key structures, but also one of its least understood. A key question is how the myosin a-helical coiled-coil tail is arranged in the backbone. At 7Å resolution, sufficient to resolve individual a-helices, the myosin tail arrangement in thick filaments from the flight muscle of the fruit fly Drosophila melanogaster is strikingly similar to the myosin tail arrangement in flight muscles of the giant waterbug Lethocerus indicus. Nearly every other thick filament feature is different. Drosophila and Lethocerus evolved separately >245 million years ago suggesting myosin tail packing into curved molecular crystalline layers forms a highly conserved thick filament building block and different properties are obtained by alterations in non-myosin proteins.

scholarly journals Characterization of components of Z-bands in the fibrillar flight muscle of Drosophila melanogaster.

1989 ◽  
Vol 109 (5) ◽  
pp. 2157-2167 ◽  
Author(s):  
J D Saide ◽  
S Chin-Bow ◽  
J Hogan-Sheldon ◽  
L Busquets-Turner ◽  
J O Vigoreaux ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Monoclonal Antibodies ◽  
Flight Muscle ◽  
Cross Reactivity ◽  
Antigenic Determinants ◽  
Immunogold Staining ◽  
Thick Filaments ◽  
The Matrix ◽  
Flight Muscles

Twelve monoclonal antibodies have been raised against proteins in preparations of Z-disks isolated from Drosophila melanogaster flight muscle. The monoclonal antibodies that recognized Z-band components were identified by immunofluorescence microscopy of flight muscle myofibrils. These antibodies have identified three Z-disk antigens on immunoblots of myofibrillar proteins. Monoclonal antibodies alpha:1-4 recognize a 90-100-kD protein which we identify as alpha-actinin on the basis of cross-reactivity with antibodies raised against honeybee and vertebrate alpha-actinins. Monoclonal antibodies P:1-4 bind to the high molecular mass protein, projectin, a component of connecting filaments that link the ends of thick filaments to the Z-band in insect asynchronous flight muscles. The anti-projectin antibodies also stain synchronous muscle, but, surprisingly, the epitopes here are within the A-bands, not between the A- and Z-bands, as in flight muscle. Monoclonal antibodies Z(210):1-4 recognize a 210-kD protein that has not been previously shown to be a Z-band structural component. A fourth antigen, resolved as a doublet (approximately 400/600 kD) on immunoblots of Drosophila fibrillar proteins, is detected by a cross reacting antibody, Z(400):2, raised against a protein in isolated honeybee Z-disks. On Lowicryl sections of asynchronous flight muscle, indirect immunogold staining has localized alpha-actinin and the 210-kD protein throughout the matrix of the Z-band, projectin between the Z- and A-bands, and the 400/600-kD components at the I-band/Z-band junction. Drosophila alpha-actinin, projectin, and the 400/600-kD components share some antigenic determinants with corresponding honeybee proteins, but no honeybee protein interacts with any of the Z(210) antibodies.

scholarly journals Hydrophobicity variations along the surface of the coiled-coil rod may mediate striated muscle myosin assembly in Caenorhabditis elegans.

1996 ◽  
Vol 135 (2) ◽  
pp. 371-382 ◽  
Author(s):  
P E Hoppe ◽  
R H Waterston
Keyword(s):  
Caenorhabditis Elegans ◽  
Striated Muscle ◽  
Coiled Coil ◽  
Thick Filament ◽  
Surface Hydrophobicity ◽  
Filament Assembly ◽  
Thick Filaments ◽  
Characteristic Variation ◽  
Muscle Myosin

Caenorhabditis elegans body wall muscle contains two isoforms of myosin heavy chain, MHC A and MHC B, that differ in their ability to initiate thick filament assembly. Whereas mutant animals that lack the major isoform, MHC B, have fewer thick filaments, mutant animals that lack the minor isoform, MHC A, contain no normal thick filaments. MHC A, but not MHC B, is present at the center of the bipolar thick filament where initiation of assembly is thought to occur (Miller, D.M.,I. Ortiz, G.C. Berliner, and H.F. Epstein. 1983. Cell. 34:477-490). We mapped the sequences that confer A-specific function by constructing chimeric myosins and testing them in vivo. We have identified two distinct regions of the MHC A rod that are sufficient in chimeric myosins for filament initiation function. Within these regions, MHC A displays a more hydrophobic rod surface, making it more similar to paramyosin, which forms the thick filament core. We propose that these regions play an important role in filament initiation, perhaps mediating close contacts between MHC A and paramyosin in an antiparallel arrangement at the filament center. Furthermore, our analysis revealed that all striated muscle myosins show a characteristic variation in surface hydrophobicity along the length of the rod that may play an important role in driving assembly and determining the stagger at which dimers associate.

scholarly journals Two distinct myosin II populations coordinate ovulatory contraction of the myoepithelial sheath in the Caenorhabditis elegans somatic gonad

2016 ◽  
Vol 27 (7) ◽  
pp. 1131-1142 ◽  
Author(s):  
Kanako Ono ◽  
Shoichiro Ono
Keyword(s):  
Caenorhabditis Elegans ◽  
Striated Muscle ◽  
Myosin Ii ◽  
Coiled Coil ◽  
The Body ◽  
Nonmuscle Myosin ◽  
Heavy Chains ◽  
Somatic Gonad ◽  
Nonmuscle Myosin Ii ◽  
Muscle Myosin

The myoepithelial sheath in the somatic gonad of the nematode Caenorhabditis elegans has nonstriated contractile actomyosin networks that produce highly coordinated contractility for ovulation of mature oocytes. Two myosin heavy chains are expressed in the myoepithelial sheath, which are also expressed in the body-wall striated muscle. The troponin/tropomyosin system is also present and essential for ovulation. Therefore, although the myoepithelial sheath has smooth muscle–like contractile apparatuses, it has a striated muscle–like regulatory mechanism through troponin/tropomyosin. Here we report that the myoepithelial sheath has a distinct myosin population containing nonmuscle myosin II isoforms, which is regulated by phosphorylation and essential for ovulation. MLC-4, a nonmuscle myosin regulatory light chain, localizes to small punctate structures and does not colocalize with large, needle-like myosin filaments containing MYO-3, a striated-muscle myosin isoform. RNA interference of MLC-4, as well as of its upstream regulators, LET-502 (Rho-associated coiled-coil forming kinase) and MEL-11 (a myosin-binding subunit of myosin phosphatase), impairs ovulation. Expression of a phosphomimetic MLC-4 mutant mimicking a constitutively active state also impairs ovulation. A striated-muscle myosin (UNC-54) appears to provide partially compensatory contractility. Thus the results indicate that the two spatially distinct myosin II populations coordinately regulate ovulatory contraction of the myoepithelial sheath.

scholarly journals A Structural Model for Phosphorylation Control of Dictyostelium Myosin II Thick Filament Assembly

1999 ◽  
Vol 147 (5) ◽  
pp. 1039-1048 ◽  
Author(s):  
Wenchuan Liang ◽  
Hans M. Warrick ◽  
James A. Spudich
Keyword(s):  
Structural Model ◽  
Myosin Ii ◽  
Coiled Coil ◽  
Thick Filament ◽  
Tail Region ◽  
Filament Assembly ◽  
Dictyostelium Myosin ◽  
Thick Filaments ◽  
Coil Structure

Myosin II thick filament assembly in Dictyostelium is regulated by phosphorylation at three threonines in the tail region of the molecule. Converting these three threonines to aspartates (3×Asp myosin II), which mimics the phosphorylated state, inhibits filament assembly in vitro, and 3×Asp myosin II fails to rescue myosin II–null phenotypes. Here we report a suppressor screen of Dictyostelium myosin II–null cells containing 3×Asp myosin II, which reveals a 21-kD region in the tail that is critical for the phosphorylation control. These data, combined with new structural evidence from electron microscopy and sequence analyses, provide evidence that thick filament assembly control involves the folding of myosin II into a bent monomer, which is unable to incorporate into thick filaments. The data are consistent with a structural model for the bent monomer in which two specific regions of the tail interact to form an antiparallel tetrameric coiled–coil structure.

scholarly journals Myosin heavy-chain kinase A from Dictyostelium possesses a novel actin-binding domain that cross-links actin filaments

2006 ◽  
Vol 395 (2) ◽  
pp. 373-383 ◽  
Author(s):  
Misty Russ ◽  
Daniel Croft ◽  
Omar Ali ◽  
Raquel Martinez ◽  
Paul A. Steimle
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Actin Filaments ◽  
Myosin Ii ◽  
Coiled Coil ◽  
Actin Binding ◽  
Coiled Coil Domain ◽  
Cross Links ◽  
Myosin Heavy Chain Kinase ◽  
Kinase A

Myosin heavy-chain kinase A (MHCK A) catalyses the disassembly of myosin II filaments in Dictyostelium cells via myosin II heavy-chain phosphorylation. MHCK A possesses a ‘coiled-coil’-enriched domain that mediates the oligomerization, cellular localization and actin-binding activities of the kinase. F-actin (filamentous actin) binding by the coiled-coil domain leads to a 40-fold increase in MHCK A activity. In the present study we examined the actin-binding characteristics of the coiled-coil domain as a means of identifying mechanisms by which MHCK A-mediated disassembly of myosin II filaments can be regulated in the cell. Co-sedimentation assays revealed that the coiled-coil domain of MHCK A binds co-operatively to F-actin with an apparent KD of approx. 0.5 μM and a stoichiometry of approx. 5:1 [actin/C(1–498)]. Further analyses indicate that the coiled-coil domain binds along the length of the actin filament and possesses at least two actin-binding regions. Quite surprisingly, we found that the coiled-coil domain cross-links actin filaments into bundles, indicating that MHCK A can affect the cytoskeleton in two important ways: (1) by driving myosin II-filament disassembly via myosin II heavy-chain phosphorylation, and (2) by cross-linking/bundling actin filaments. This discovery, along with other supporting data, suggests a model in which MHCK A-mediated bundling of actin filaments plays a central role in the recruitment and activation of the kinase at specific sites in the cell. Ultimately this provides a means for achieving the robust and highly localized disruption of myosin II filaments that facilitates polarized changes in cell shape during processes such as chemotaxis, cytokinesis and multicellular development.

Tropomyosin-Based Regulation of the Actin Cytoskeleton in Time and Space

2008 ◽  
Vol 88 (1) ◽  
pp. 1-35 ◽  
Author(s):  
Peter Gunning ◽  
Geraldine O’neill ◽  
Edna Hardeman
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Filaments ◽  
Striated Muscle ◽  
Coiled Coil ◽  
Cell Types ◽  
Actin Binding ◽  
Regulation Of Expression ◽  
Wide Range ◽  
Muscle Tropomyosin ◽  
The Many

Tropomyosins are rodlike coiled coil dimers that form continuous polymers along the major groove of most actin filaments. In striated muscle, tropomyosin regulates the actin-myosin interaction and, hence, contraction of muscle. Tropomyosin also contributes to most, if not all, functions of the actin cytoskeleton, and its role is essential for the viability of a wide range of organisms. The ability of tropomyosin to contribute to the many functions of the actin cytoskeleton is related to the temporal and spatial regulation of expression of tropomyosin isoforms. Qualitative and quantitative changes in tropomyosin isoform expression accompany morphogenesis in a range of cell types. The isoforms are segregated to different intracellular pools of actin filaments and confer different properties to these filaments. Mutations in tropomyosins are directly involved in cardiac and skeletal muscle diseases. Alterations in tropomyosin expression directly contribute to the growth and spread of cancer. The functional specificity of tropomyosins is related to the collaborative interactions of the isoforms with different actin binding proteins such as cofilin, gelsolin, Arp 2/3, myosin, caldesmon, and tropomodulin. It is proposed that local changes in signaling activity may be sufficient to drive the assembly of isoform-specific complexes at different intracellular sites.

scholarly journals THE FILAMENT LATTICE OF COCKROACH THORACIC MUSCLE

1968 ◽  
Vol 36 (3) ◽  
pp. 433-442 ◽  
Author(s):  
Martin Hagopian ◽  
David Spiro
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Flight Muscle ◽  
Insect Flight ◽  
Thick Filament ◽  
Leucophaea Maderae ◽  
Thick Filaments ◽  
Femoral Muscle ◽  
Flight Muscles ◽  
Characteristic 3

The fine structure of the tergo-coxal muscle of the cockroach, Leucophaea maderae, has been studied with the electron microscope. This muscle differs from some other types of insect flight muscles inasmuch as the ratio of thin to thick filaments is 4 instead of the characteristic 3. The cockroach flight muscle also differs from the cockroach femoral muscle in thin to thick filament ratios and diameters and in lengths of thick filaments. A comparison of these latter three parameters in a number of vertebrate and invertebrate muscles suggests in general that the diameters and lengths of the thick filaments and thin to thick filament ratios are related.

scholarly journals Structure of myosin filaments from relaxed Lethocerus flight muscle by cryo-EM at 6 Å resolution

2016 ◽  
Vol 2 (9) ◽  
pp. e1600058 ◽  
Author(s):  
Zhongjun Hu ◽  
Dianne W. Taylor ◽  
Michael K. Reedy ◽  
Robert J. Edwards ◽  
Kenneth A. Taylor
Keyword(s):  
Flight Muscle ◽  
Three Dimensional ◽  
Coiled Coil ◽  
Thick Filament ◽  
Coiled Coils ◽  
Muscle Physiology ◽  
Layer Arrangement ◽  
Thick Filaments ◽  
Unusual Position ◽  
Filament Structure

We describe a cryo–electron microscopy three-dimensional image reconstruction of relaxed myosin II–containing thick filaments from the flight muscle of the giant water bug Lethocerus indicus. The relaxed thick filament structure is a key element of muscle physiology because it facilitates the reextension process following contraction. Conversely, the myosin heads must disrupt their relaxed arrangement to drive contraction. Previous models predicted that Lethocerus myosin was unique in having an intermolecular head-head interaction, as opposed to the intramolecular head-head interaction observed in all other species. In contrast to the predicted model, we find an intramolecular head-head interaction, which is similar to that of other thick filaments but oriented in a distinctly different way. The arrangement of myosin’s long α-helical coiled-coil rod domain has been hypothesized as either curved layers or helical subfilaments. Our reconstruction is the first report having sufficient resolution to track the rod α helices in their native environment at resolutions ~5.5 Å, and it shows that the layer arrangement is correct for Lethocerus. Threading separate paths through the forest of myosin coiled coils are four nonmyosin peptides. We suggest that the unusual position of the heads and the rod arrangement separated by nonmyosin peptides are adaptations for mechanical signal transduction whereby applied tension disrupts the myosin heads as a component of stretch activation.

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