scholarly journals Flexural Stiffness of Myosin Va Subdomains as Measured from Tethered Particle Motion

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Arthur J. Michalek ◽  
Guy G. Kennedy ◽  
David M. Warshaw ◽  
M. Yusuf Ali
Keyword(s):  
Molecular Motor ◽  
Coiled Coil ◽  
Flexural Stiffness ◽  
Actin Network ◽  
Lever Arm ◽  
Cargo Transport ◽  
Single Lever ◽  
Tethered Particle Motion ◽  
Myosin Va ◽  
Order Of Magnitude

Myosin Va (MyoVa) is a processive molecular motor involved in intracellular cargo transport on the actin cytoskeleton. The motor’s processivity and ability to navigate actin intersections are believed to be governed by the stiffness of various parts of the motor’s structure. Specifically, changes in calcium may regulate motor processivity by altering the motor’s lever arm stiffness and thus its interhead communication. In order to measure the flexural stiffness of MyoVa subdomains, we use tethered particle microscopy, which relates the Brownian motion of fluorescent quantum dots, which are attached to various single- and double-headed MyoVa constructs bound to actin in rigor, to the motor’s flexural stiffness. Based on these measurements, the MyoVa lever arm and coiled-coil rod domain have comparable flexural stiffness (0.034 pN/nm). Upon addition of calcium, the lever arm stiffness is reduced 40% as a result of calmodulins potentially dissociating from the lever arm. In addition, the flexural stiffness of the full-length MyoVa construct is an order of magnitude less stiff than both a single lever arm and the coiled-coil rod. This suggests that the MyoVa lever arm-rod junction provides a flexible hinge that would allow the motor to maneuver cargo through the complex intracellular actin network.

scholarly journals A Coiled-Coil Domain of Melanophilin Is Essential for Myosin Va Recruitment and Melanosome Transport in Melanocytes

2006 ◽  
Vol 17 (11) ◽  
pp. 4720-4735 ◽  
Author(s):  
Alistair N. Hume ◽  
Abul K. Tarafder ◽  
José S. Ramalho ◽  
Elena V. Sviderskaya ◽  
Miguel C. Seabra
Keyword(s):  
Coiled Coil ◽  
Binding Domain ◽  
Actin Binding ◽  
Binding Studies ◽  
Null Cell ◽  
Coiled Coil Region ◽  
Actin Binding Domain ◽  
Transport Assay ◽  
Myosin Va

Melanophilin (Mlph) regulates retention of melanosomes at the peripheral actin cytoskeleton of melanocytes, a process essential for normal mammalian pigmentation. Mlph is proposed to be a modular protein binding the melanosome-associated protein Rab27a, Myosin Va (MyoVa), actin, and microtubule end-binding protein (EB1), via distinct N-terminal Rab27a-binding domain (R27BD), medial MyoVa-binding domain (MBD), and C-terminal actin-binding domain (ABD), respectively. We developed a novel melanosome transport assay using a Mlph-null cell line to study formation of the active Rab27a:Mlph:MyoVa complex. Recruitment of MyoVa to melanosomes correlated with rescue of melanosome transport and required intact R27BD together with MBD exon F–binding region (EFBD) and unexpectedly a potential coiled-coil forming sequence within ABD. In vitro binding studies indicate that the coiled-coil region enhances binding of MyoVa by Mlph MBD. Other regions of Mlph reported to interact with MyoVa globular tail, actin, or EB1 are not essential for melanosome transport rescue. The strict correlation between melanosomal MyoVa recruitment and rescue of melanosome distribution suggests that stable interaction with Mlph and MyoVa activation are nondissociable events. Our results highlight the importance of the coiled-coil region together with R27BD and EFBD regions of Mlph in the formation of the active melanosomal Rab27a-Mlph-MyoVa complex.

Mechanical Organization of Cantileverlike Sessile Organisms: Sea Anemones

1977 ◽  
Vol 69 (1) ◽  
pp. 127-142
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Elastic Modulus ◽  
Body Wall ◽  
Local Buckling ◽  
Beam Theory ◽  
Extension Rate ◽  
Flexural Stiffness ◽  
Sea Anemones ◽  
Order Of Magnitude ◽  
Anthopleura Xanthogrammica ◽  
Sessile Organisms

Engineering beam theory has been used to analyse the ways in which body shape and elastic modulus of two species of sea anemones affect their mechanical responses to flow. 1.Anthopleura xanthogrammica is exposed to wave action, but because it is short, wide, and thick-walled, maximum tensile stresses in its body walls due to flow forces are an order of magnitude lower than those in the tall, slim, thin-walled, calm-water sea anemone Metridium senile.2. The elastic modulus of M. senile body wall is more dependent on extension rate than is that of A. xanthogrammica. Because the extension rate of M. senile body wall in tidal currents is higher than that of A. xanthogrammica in wave surge, the moduli of walls from these species when exposed to such flow conditions are similar, between 0.1 and 0.3 MN.m−2.3. The flexural stiffness of M. senile is lowest in the upper column where the anemones bend in currents: this orients their filter-feeding oral discs normal to the currents. The flexural stiffness of A. xanthogrammica is one to two orders of magnitude higher than that of M. senile; A. xanthogrammica remain upright in wave surge and feed on mussels that fall on their oral discs.4. The deflexions of these anemones predicted using beam theory are consistent with those observed in nature.5. The critical stress to produce local buckling is an order of magnitude lower for M. senile than for A. xanthogrammica.6. Several general principles of the organization of cantilever-like sessile organisms are revealed by this study of sea anemones.

scholarly journals Optimized filopodia formation requires myosin tail domain cooperation

2019 ◽  
Vol 116 (44) ◽  
pp. 22196-22204
Author(s):  
Ashley L. Arthur ◽  
Livia D. Songster ◽  
Helena Sirkia ◽  
Akash Bhattacharya ◽  
Carlos Kikuti ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Tail Domain ◽  
Tail Region ◽  
Lever Arm ◽  
Coiled Coil Domain ◽  
And Function

Filopodia are actin-filled protrusions employed by cells to interact with their environment. Filopodia formation in Amoebozoa and Metazoa requires the phylogenetically diverse MyTH4-FERM (MF) myosins DdMyo7 and Myo10, respectively. While Myo10 is known to form antiparallel dimers, DdMyo7 lacks a coiled-coil domain in its proximal tail region, raising the question of how such divergent motors perform the same function. Here, it is shown that the DdMyo7 lever arm plays a role in both autoinhibition and function while the proximal tail region can mediate weak dimerization, and is proposed to be working in cooperation with the C-terminal MF domain to promote partner-mediated dimerization. Additionally, a forced dimer of the DdMyo7 motor is found to weakly rescue filopodia formation, further highlighting the importance of the C-terminal MF domain. Thus, weak dimerization activity of the DdMyo7 proximal tail allows for sensitive regulation of myosin activity to prevent inappropriate activation of filopodia formation. The results reveal that the principles of MF myosin-based filopodia formation are conserved via divergent mechanisms for dimerization.

scholarly journals Myosin Va Vesicular Transport is Modulated by Actin Filament Density, Orientation, and Polarity in an In Vitro 3D Actin Network

2018 ◽  
Vol 114 (3) ◽  
pp. 211a
Author(s):  
Andrew T. Lombardo ◽  
Shane R. Nelson ◽  
Guy G. Kennedy ◽  
Kathleen M. Trybus ◽  
Sam Walcott ◽  
...  
Keyword(s):  
Actin Filament ◽  
Vesicular Transport ◽  
Actin Network ◽  
Myosin Va

A Stable and Fast Operating Door for Use With Pipelines and Launchers / Receivers of Various Diameters

2000 ◽  
Author(s):  
Abu Salim ◽  
Marney D. Perry ◽  
John A. Krogue ◽  
Allen Walker
Keyword(s):  
Oil And Gas ◽  
Cost Effective ◽  
Easy Access ◽  
Gas Pipelines ◽  
Rotation Direction ◽  
Lever Arm ◽  
Prime Concern ◽  
Single Lever ◽  
Receiver Unit ◽  
Opening And Closing

The oil and gas pipelines are spread around the world in all nations as complex networks. The increased usage of gas is rapidly increasing this network. These networks are generally made from various diameters of pipes. The pipelines are serviced on as required basis, using pig launcher and receivers to suit the pipe diameter. Pigs of different types may be launched in different sequences, to clean the pipes and to obtain various data related to pipe condition and location. The pig launching and receiving process uses rapid pressure changes in the launcher and receiver and some magnitude of impact may be experienced by the unit. This process also requires frequent access to the launcher/receiver unit. To have an efficient and cost effective usage of the launcher/receiver unit, it is essential to have a door mechanism, which is safe, robust, capable of the above loading conditions, requires minimum service and is easy to use. PECO has recently developed & designed a door, which incorporates ail the above requirements. The door was put to high pressure testing and the test results were so encouraging that PECO named it SafeLock® Closure. The design was developed with gas pipelines in mind. However it is equally applicable to vessels, exchangers and other metal openings where quick, frequent and easy access is required. Safety has been the prime concern through out the design and development process of this closure. Therefore the final product has resulted in a very safe closure. The initial design of the SafeLock® door / closure used a spring load to make it easy in operation. This was removed in the later design. The segmental blocks, usually called C-ring segments, are operated to move in and out of the shell-sub annulus. The closure opening and closing is performed by the use of a single lever arm. This way only one person can operate (open and close) the door / closure. For opening and closing, the lever-arm needs to be rotated less than 40 degree angle. The rotation direction of the lever arm in closing is reverse of that in opening. The door / head can be fully retrieved from the shell-sub and rest by the side of the launcher/receiver to provide complete access to the opening. This door / closure provides quick access to launcher / receiver, pig traps, meter provers, filter vessel, scrubber, scraper, manway to pressure vessel, etc. This closure can be mounted in the vertical or horizontal position. During change of filter elements, launching a pig, quick access to container under pressure, this closure door is designed to provide a safe and fast service. The construction, operation, design details and application of the new closure door are included in this paper and explained with the help of the design diagrams and photographs.

scholarly journals Transport of Lipid Vesicles by the Molecular Motor Myosin Va

2013 ◽  
Vol 19 (S2) ◽  
pp. 154-155
Author(s):  
S. Nelson ◽  
D.M. Warshaw
Keyword(s):  
Molecular Motor ◽  
Lipid Vesicles ◽  
Myosin Va

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

scholarly journals Intracellular cargo transport by single-headed kinesin motors

2019 ◽  
Vol 116 (13) ◽  
pp. 6152-6161 ◽  
Author(s):  
Kristin I. Schimert ◽  
Breane G. Budaitis ◽  
Dana N. Reinemann ◽  
Matthew J. Lang ◽  
Kristen J. Verhey
Keyword(s):  
Intracellular Transport ◽  
Motor Coordination ◽  
Optical Trap ◽  
Coiled Coil ◽  
Force Output ◽  
Cellular Assays ◽  
Cellular Events ◽  
Cargo Transport ◽  
In Cells

Kinesin motor proteins that drive intracellular transport share an overall architecture of two motor domain-containing subunits that dimerize through a coiled-coil stalk. Dimerization allows kinesins to be processive motors, taking many steps along the microtubule track before detaching. However, whether dimerization is required for intracellular transport remains unknown. Here, we address this issue using a combination of in vitro and cellular assays to directly compare dimeric motors across the kinesin-1, -2, and -3 families to their minimal monomeric forms. Surprisingly, we find that monomeric motors are able to work in teams to drive peroxisome dispersion in cells. However, peroxisome transport requires minimal force output, and we find that most monomeric motors are unable to disperse the Golgi complex, a high-load cargo. Strikingly, monomeric versions of the kinesin-2 family motors KIF3A and KIF3B are able to drive Golgi dispersion in cells, and teams of monomeric KIF3B motors can generate over 8 pN of force in an optical trap. We find that intracellular transport and force output by monomeric motors, but not dimeric motors, are significantly decreased by the addition of longer and more flexible motor-to-cargo linkers. Together, these results suggest that dimerization of kinesin motors is not required for intracellular transport; however, it enables motor-to-motor coordination and high force generation regardless of motor-to-cargo distance. Dimerization of kinesin motors is thus critical for cellular events that require an ability to generate or withstand high forces.

scholarly journals 1P-138 Role of the lever arm in the subunit coordination in myosin V(Molecular motor, The 47th Annual Meeting of the Biophysical Society of Japan)

2009 ◽  
Vol 49 (supplement) ◽  
pp. S84
Author(s):  
Yusuke Oguchi ◽  
Sergey V. Mikhailenko ◽  
Takashi Ohki ◽  
Adrian O. Olivares ◽  
Enrique M. De La Cruz ◽  
...  
Keyword(s):  
Annual Meeting ◽  
Molecular Motor ◽  
Myosin V ◽  
Lever Arm ◽  
Biophysical Society

scholarly journals 3P159 Investigation of the mechanism of cooperative cargo transport by multiple kinesins(Molecular motor,Poster,The 52th Annual Meeting of the Biophysical Society of Japan(BSJ2014))

2014 ◽  
Vol 54 (supplement1-2) ◽  
pp. S275
Author(s):  
Sawairi Naoto ◽  
Ariga Takayuki ◽  
Iwaki Mitsuhiro ◽  
Tomishige Michio ◽  
Hayashi Kumiko
Keyword(s):  
Annual Meeting ◽  
Molecular Motor ◽  
Cargo Transport ◽  
Biophysical Society
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