The reciprocal coordination and mechanics of molecular motors in living cells

Laib, Jeneva A.; Marin, John A.; Bloodgood, Robert A.; Guilford, William H.

doi:10.1073/pnas.0809849106

Cited by 64 publications

(59 citation statements)

References 50 publications

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“…A similar mechanism has been proposed for regulating kinesin/dynein transport on microtubules via the presence of tau-protein binding to the microtubule (42). Modifiers that alter the number of engaged motors in effect would eliminate or bias (43)(44)(45) the inherent tug of war that would exist between opposing motors as observed in this study. Future efforts to define the various regulatory mechanisms that govern intracellular transport will benefit from parallel in vitro single molecule biophysical and in vivo cell biological approaches.…”

Section: In-phasementioning

confidence: 59%

Myosin Va and myosin VI coordinate their steps while engaged in an in vitro tug of war during cargo transport

Safer³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Myosin Va (myoV) and myosin VI (myoVI) are processive molecular motors that transport cargo in opposite directions on actin tracks. Because these motors may bind to the same cargo in vivo, we developed an in vitro "tug of war" to characterize the stepping dynamics of single quantum-dot-labeled myoV and myoVI motors linked to a common cargo. MyoV dominates its myoVI partner 79% of the time. Regardless of which motor wins, its stepping rate slows due to the resistive load of the losing motor (myoV, 2.1 pN; myoVI, 1.4 pN). Interestingly, the losing motor steps backward in synchrony with the winning motor. With ADP present, myoVI acts as an anchor to prevent myoV from stepping forward. This model system emphasizes the physical communication between opposing motors bound to a common cargo and highlights the potential for modulating this interaction by changes in the cell's ionic milieu.intracellular transport | motility assay | processivity | single molecule biophysics I ntracellular cargo transport relies on at least two classes of myosin molecular motors to navigate the actin cytoskeleton. Class V (myoV) and class VI (myoVI) myosins are double-headed motors that transport cargo in opposite directions along polarized actin filament tracks (1, 2). These motors convert the energy of ATP hydrolysis into force and motion and in doing so step processively on actin in a hand-over-hand fashion. With the plusends of actin filaments oriented toward the cell periphery, myoV transport contributes to exocytosis, whereas myoVI transport is critical to endocytosis (1, 2). Ensembles of molecular motors share the responsibility for transporting a single vesicle. For example, approximately 60 myoV motors coat a melanosome, although a smaller number is likely to be engaged with the track at any given time (3). Transport can also be bidirectional when oppositely directed motors are operative, as for axonal transport by the microtubule-based motors, kinesin and dynein (4, 5). With myoV and myoVI colocalizing to organelles (6, 7), these motors may engage in a virtual tug of war. If so, how do these oppositely directed myosin motors mechanically interact so that cargo is efficiently delivered to its destination?Individual motors within a transport ensemble may coordinate, cooperate, or mechanically impede one another, but determining by which mode they operate is complicated by the cargo geometry, the number and directionality of engaged motors, and the physical challenges presented by the dense actin cytoskeleton. Therefore, investigators have designed in vitro experiments to limit the number of coupled motors so that mechanistic modeling efforts were tractable (8-11). For these models, the velocity and direction of cargo transport generated by ensembles of antagonistic motors depended solely on the relative number of motors pulling in either direction (12, 13). The mechanical interactions between motors and the resultant stepping dynamics of each motor within the ensemble were beyond the predictive capacity of these models. Therefore, ...

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Section: In-phasementioning

confidence: 59%

Myosin Va and myosin VI coordinate their steps while engaged in an in vitro tug of war during cargo transport

Safer³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Quantitative analyses of motor numbers in living cells have shown that a few motors of each type bind to the same organelle, where they coordinate and control each other's activity (3,6,7). The number of bound motors is remarkably similar in different systems, usually ranging from one to five motors of each type (7)(8)(9)(10), although in a few cases larger numbers were also reported (11,12). The presence of both kinesin and dynein on a cargo implies that both motors may be pulling on the cargo at the same time, which leads to essentially no motion of the cargo.…”

mentioning

confidence: 97%

Transient binding of dynein controls bidirectional long-range motility of early endosomes

Schuster

Lipowsky

Assmann³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

141

258

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In many cell types, bidirectional long-range endosome transport is mediated by the opposing motor proteins dynein and kinesin-3. Here we use a fungal model system to investigate how both motors cooperate in early endosome (EE) motility. It was previously reported that Kin3, a member of the kinesin-3 family, and cytoplasmic dynein mediate bidirectional motility of EEs in the fungus Ustilago maydis. We fused the green fluorescent protein to the endogenous dynein heavy chain and the kin3 gene and visualized both motors and their cargo in the living cells. Whereas kinesin-3 was found on anterograde and retrograde EEs, dynein motors localize only to retrograde organelles. Live cell imaging shows that binding of retrograde moving dynein to anterograde moving endosomes changes the transport direction of the organelles. When dynein is leaving the EEs, the organelles switch back to anterograde kinesin-3-based motility. Quantitative photobleaching and comparison with nuclear pores as an internal calibration standard show that single dynein motors and four to five kinesin-3 motors bind to the organelles. These data suggest that dynein controls kinesin-3 activity on the EEs and thereby determines the longrange motility behavior of the organelles. membrane trafficking | modeling

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“…The tug-of-war model supports the idea that the two motor proteins compete with each other to move the cargo in their desired direction [16][17][18][19] . On the contrary, the coordination model suggests that the two types of motor proteins are coordinated by certain molecular signals so that only one is activated while the other is deactivated during transport [20][21][22][23][24] , and a coordination complex might exist to regulate the motors 25,26 , although this coordination complex was proved unnecessary to explain the bidirectional cargo transport 17 . It was also proposed that the two models coexist in the microtubule-based transport, while tug-of-war can be deemed as one mechanism of 'coordination' 15 .…”

mentioning

confidence: 99%

Rotational dynamics of cargos at pauses during axonal transport

Sun

Wang

et al. 2012

Nat Commun

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Direct visualization of axonal transport in live neurons is essential for our understanding of the neuronal functions and the working mechanisms of microtubule-based motor proteins. Here we use the high-speed single particle orientation and rotational tracking technique to directly visualize the rotational dynamics of cargos in both active directional transport and pausing stages of axonal transport, with a temporal resolution of 2 ms. Both long and short pauses are imaged, and the correlations between the pause duration, the rotational behaviour of the cargo at the pause, and the moving direction after the pause are established. Furthermore, the rotational dynamics leading to switching tracks are visualized in detail. These first-time observations of cargo's rotational dynamics provide new insights on how kinesin and dynein motors take the cargo through the alternating stages of active directional transport and pause.

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The reciprocal coordination and mechanics of molecular motors in living cells

Cited by 64 publications

References 50 publications

Myosin Va and myosin VI coordinate their steps while engaged in an in vitro tug of war during cargo transport

Myosin Va and myosin VI coordinate their steps while engaged in an in vitro tug of war during cargo transport

Transient binding of dynein controls bidirectional long-range motility of early endosomes

Rotational dynamics of cargos at pauses during axonal transport

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