Dynein pulls microtubules without rotating its stalk

Ueno, Hironori; Yasunaga, Takuo; Shingyoji, Chikako; Hirose, Keiko

doi:10.1073/pnas.0808194105

Cited by 83 publications

(43 citation statements)

References 38 publications

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“…Two distinct binding conformations would further agree with a study by Gibbons,et al (41) that describes two stalk conformations with different MT affinity. Furthermore, electron microscopic images of sea urchin outer arm dynein showed no significant change in the angle of stalk attachment between different nucleotide states (37) indicating that, during stepping, the stalk conformation within one motor domain remains stable.…”

Section: Discussionmentioning

confidence: 96%

“…Pi may play a critical role in providing a directional bias to force production, by altering the relative orientation of the two motor domains upon MT binding. Electron microscopic studies illustrate that the two motor domains of dynein can be in close contact with each other (36,37). Thus, a head-head interaction and/or relative head-head orientation could determine which of the two heads binds first, thereby influencing the binding position of the second motor domain and thus the directionality.…”

Section: Discussionmentioning

confidence: 99%

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Two independent switches regulate cytoplasmic dynein’s processivity and directionality

Walter

Koonce²,

Brenner³

et al. 2012

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

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Cytoplasmic dynein is a microtubule-based molecular motor that participates in a multitude of cell activities, from cell division to organelle transport. Unlike kinesin and myosin, where different tasks are performed by highly specialized members of these superfamilies, a single form of the dynein heavy chain is utilized for different functions. This versatility demands an extensive regulation of motor function. Using an improved application of an optical trap, we were now able to demonstrate that cytoplasmic dynein can generate a discrete power stroke as well as a processive walk in either direction; i.e., towards the plus-or towards the minus-end of a microtubule. Thus, dynein's motor functions can be described by four basic modes of motion: processive and nonprocessive movement, and movement in the forward and reverse directions. Importantly, these four modes of movement can be controlled by two switches. One switch, based on phosphate, determines the directionality of movement. The second switch, depending on magnesium, converts cytoplasmic dynein from a nonprocessive to a processive motor. The two switches can be triggered separately or jointly by changing concentrations of phosphate and magnesium in the local environment. The control of four modes of movement by two switches has major implications for our understanding of the cellular functions and regulation of cytoplasmic dynein. Based on recent studies of dynein's structure we are able to draw new conclusions on cytoplasmic dynein's stepping mechanism. molecular motors | motor mechanics | single molecule I n eukaryotic cells almost all organelle transport is performed by the three families of cytoskeleton-based molecular motors, myosin, kinesin, and dynein (1-3). While myosin and kinesin have evolved into large families with multiple members, each of which specialized for different tasks, a single dynein heavy chain performs all of the dynein related activities in the cytoplasm of eukaryotic cells (1).One key function of cytoplasmic dynein is to power cargo transport over long distances. Here, motor processivity is required if long distance transport is to be achieved by a single motor molecule. To facilitate cargo delivery processivity must be switched off, when the target area is reached. Regulation becomes even more important when multiple motors of the same or even different type act together. For example, a model situation for the cooperation of different motors occurs during axonal transport driven by kinesin-1 and cytoplasmic dynein. During long distance travel, frequent changes in direction are observed. It is generally thought that the reversals of direction result from counteracting motor activity (4, 5). Though, a simple tug-of-war model in which only the winner determines the direction of movement appears rather inefficient to deliver cargo to specific locations. Moreover, it has been demonstrated in vitro and in vivo that dynein's activity dominates over kinesin (6, 7). Therefore, being able to modulate dynein's processivity and directional...

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Two independent switches regulate cytoplasmic dynein’s processivity and directionality

Walter

Koonce²,

Brenner³

et al. 2012

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

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“…This suggestion does not negate the possibility that LC1 also plays an important role in stabilizing the motor domain with respect to the A-tubule. This might ensure that the AAA ring remains a constant distance from the A-tubule within a bent region of the flagellum when the interdoublet gap increases (35) and/or prevent or modulate the ability of the AAA ring to move with respect to the axonemal long axis (36,37); this latter feature might convert the ␥ HC motor into an ATP-dependent brake that limits sliding.…”

Section: Discussionmentioning

confidence: 99%

Functional Architecture of the Outer Arm Dynein Conformational Switch

King

Patel‐King

2012

Journal of Biological Chemistry

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Background: Ciliary dyneins monitor and respond to the mechanical state or curvature of the microtubular axoneme. Results: NMR chemical shift mapping and binding assays define functional subdomains within a key component (LC1) of this system. Conclusion: LC1 provides a direct tether between a dynein motor unit and the microtubule that modulates motor function. Significance: This study provides insight into the mechanism by which dyneins are coordinated during ciliary beating.

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“…Rotations of the ring may enable dynein to reach various tubulin subunits during a step (33). In contrast, other structural studies of axonemal dynein report that the stalk and ring domain rotate much less relative to the MT throughout different nucleotide states (34,35). In an alternate model to a power-stroke mechanism, the stalk and ring adopt an almost fixed orientation relative to the MT and the linker acts as a lever to produce force by straightening and thereby pulling cargo forward (14,31,36) (Fig.…”

mentioning

confidence: 93%

Angular measurements of the dynein ring reveal a stepping mechanism dependent on a flexible stalk

Lippert

Dadosh

Hadden

et al. 2017

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

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The force-generating mechanism of dynein differs from the forcegenerating mechanisms of other cytoskeletal motors. To examine the structural dynamics of dynein's stepping mechanism in real time, we used polarized total internal reflection fluorescence microscopy with nanometer accuracy localization to track the orientation and position of single motors. By measuring the polarized emission of individual quantum nanorods coupled to the dynein ring, we determined the angular position of the ring and found that it rotates relative to the microtubule (MT) while walking. Surprisingly, the observed rotations were small, averaging only 8.3°, and were only weakly correlated with steps. Measurements at two independent labeling positions on opposite sides of the ring showed similar small rotations. Our results are inconsistent with a classic power-stroke mechanism, and instead support a flexible stalk model in which interhead strain rotates the rings through bending and hinging of the stalk. Mechanical compliances of the stalk and hinge determined based on a 3.3-μs molecular dynamics simulation account for the degree of ring rotation observed experimentally. Together, these observations demonstrate that the stepping mechanism of dynein is fundamentally different from the stepping mechanisms of other well-studied MT motors, because it is characterized by constant small-scale fluctuations of a large but flexible structure fully consistent with the variable stepping pattern observed as dynein moves along the MT.ynein is a molecular motor that walks processively toward the minus end of microtubules (MTs) in an ATP-dependent manner (1-3). Axonemal dyneins drive the motility of eukaryotic cilia and flagella, whereas cytoplasmic dynein is responsible for a wide range of functions within eukaryotic cells, including the retrograde transport of cargo such as autophagosomes in neurons (4), alignment of the mitotic spindle (5, 6), and chromosome segregation during mitosis (7). Disruption of dynein-mediated neuronal transport has been implicated in neurodegeneration (8), and mutations in dynein and dynein-associated proteins can cause a range of diseases, including spinal muscular atrophy (9, 10), lissencephaly (11) and Charcot-Marie-Tooth disease type 2 (reviewed in ref. 12). Despite the importance of dynein function, the mechanism by which dynein walks along the MT is not yet well understood.The motor domains of dynein are formed from six concatenated AAA domains, interrupted by a long, antiparallel, coiled-coil stalk that emerges from AAA4 and terminates in the microtubulebinding domain (MTBD) and the buttress that extends from AAA5 and is thought to stabilize the stalk (13,14). Two motor domains form a dimer via their N-terminal tails (2, 3). ATP binding and hydrolysis drive dynein mechanochemistry; the binding of ATP to AAA1 induces a conformational change leading to dissociation of the MTBD from the MT. Hydrolysis on the dissociated head induces a primed conformation that then rebinds to the MT. The forward step, or power stroke,...

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Dynein pulls microtubules without rotating its stalk

Cited by 83 publications

References 38 publications

Two independent switches regulate cytoplasmic dynein’s processivity and directionality

Two independent switches regulate cytoplasmic dynein’s processivity and directionality

Functional Architecture of the Outer Arm Dynein Conformational Switch

Angular measurements of the dynein ring reveal a stepping mechanism dependent on a flexible stalk

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