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Tension on the linker gates the ATP-dependent release of dynein from microtubules.

Cleary FB, Dewitt MA, Bilyard T, Htet ZM, Belyy V, Chan DD, Chang AY, Yildiz A - Nat Commun (2014)

Bottom Line: Here, by engineering the mechanical and catalytic properties of the motor, we show that dynein processivity minimally requires a single active head and a second inert MT-binding domain.Processivity arises from a high ratio of MT-bound to unbound time, and not from interhead communication.In addition, nucleotide-dependent microtubule release is gated by tension on the linker domain.

View Article: PubMed Central - PubMed

Affiliation: Biophysics Graduate Group, University of California, Berkeley, California 94720, USA.

ABSTRACT
Cytoplasmic dynein is a dimeric motor that transports intracellular cargoes towards the minus end of microtubules (MTs). In contrast to other processive motors, stepping of the dynein motor domains (heads) is not precisely coordinated. Therefore, the mechanism of dynein processivity remains unclear. Here, by engineering the mechanical and catalytic properties of the motor, we show that dynein processivity minimally requires a single active head and a second inert MT-binding domain. Processivity arises from a high ratio of MT-bound to unbound time, and not from interhead communication. In addition, nucleotide-dependent microtubule release is gated by tension on the linker domain. Intramolecular tension sensing is observed in dynein's stepping motion at high interhead separations. On the basis of these results, we propose a quantitative model for the stepping characteristics of dynein and its response to chemical and mechanical perturbation.

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A model for dynein motility(a) Two proposed mechanisms of dynein stepping. (Left) When the heads are close to each other, either head can release the MT and step forward upon binding ATP. (Right) When the heads are far apart, tension on the linker prevents ATP-dependent MT release, and the asymmetry of the release rates under tension favors the trailing head to take a step. (b) A representative Monte-Carlo simulation of dynein motility shows stepping of the two head domains (blue and red). (c) The trailing head is more likely to take a step in simulated traces as the interhead separation increases. The data shown is the average of 200 simulations (± SD). (d) The average velocity of 200 100 s simulated traces (± SEM) agrees well with measured velocities for various dynein mutants (± SEM, n > 100). The results of the model are within ±15% of the experimental data.
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Figure 6: A model for dynein motility(a) Two proposed mechanisms of dynein stepping. (Left) When the heads are close to each other, either head can release the MT and step forward upon binding ATP. (Right) When the heads are far apart, tension on the linker prevents ATP-dependent MT release, and the asymmetry of the release rates under tension favors the trailing head to take a step. (b) A representative Monte-Carlo simulation of dynein motility shows stepping of the two head domains (blue and red). (c) The trailing head is more likely to take a step in simulated traces as the interhead separation increases. The data shown is the average of 200 simulations (± SD). (d) The average velocity of 200 100 s simulated traces (± SEM) agrees well with measured velocities for various dynein mutants (± SEM, n > 100). The results of the model are within ±15% of the experimental data.

Mentions: We combined our experimental results and developed a quantitative model for dynein motility. We envisioned that a head can release from the MT either through ATP binding or by tension (Fig. 6a). At low separations, the heads are fully uncoordinated. One of the heads binds ATP and takes a step with a rate of 8 s−1 32. The other head serves as a tether to prevent release of the motor from MT18. At high interhead separations, tension on the linkers prohibits release of a head from MT through ATP binding (Fig. 6a). In this case, a head releases from MTs under tension and relieves the tension by stepping towards the tethered head.


Tension on the linker gates the ATP-dependent release of dynein from microtubules.

Cleary FB, Dewitt MA, Bilyard T, Htet ZM, Belyy V, Chan DD, Chang AY, Yildiz A - Nat Commun (2014)

A model for dynein motility(a) Two proposed mechanisms of dynein stepping. (Left) When the heads are close to each other, either head can release the MT and step forward upon binding ATP. (Right) When the heads are far apart, tension on the linker prevents ATP-dependent MT release, and the asymmetry of the release rates under tension favors the trailing head to take a step. (b) A representative Monte-Carlo simulation of dynein motility shows stepping of the two head domains (blue and red). (c) The trailing head is more likely to take a step in simulated traces as the interhead separation increases. The data shown is the average of 200 simulations (± SD). (d) The average velocity of 200 100 s simulated traces (± SEM) agrees well with measured velocities for various dynein mutants (± SEM, n > 100). The results of the model are within ±15% of the experimental data.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4129465&req=5

Figure 6: A model for dynein motility(a) Two proposed mechanisms of dynein stepping. (Left) When the heads are close to each other, either head can release the MT and step forward upon binding ATP. (Right) When the heads are far apart, tension on the linker prevents ATP-dependent MT release, and the asymmetry of the release rates under tension favors the trailing head to take a step. (b) A representative Monte-Carlo simulation of dynein motility shows stepping of the two head domains (blue and red). (c) The trailing head is more likely to take a step in simulated traces as the interhead separation increases. The data shown is the average of 200 simulations (± SD). (d) The average velocity of 200 100 s simulated traces (± SEM) agrees well with measured velocities for various dynein mutants (± SEM, n > 100). The results of the model are within ±15% of the experimental data.
Mentions: We combined our experimental results and developed a quantitative model for dynein motility. We envisioned that a head can release from the MT either through ATP binding or by tension (Fig. 6a). At low separations, the heads are fully uncoordinated. One of the heads binds ATP and takes a step with a rate of 8 s−1 32. The other head serves as a tether to prevent release of the motor from MT18. At high interhead separations, tension on the linkers prohibits release of a head from MT through ATP binding (Fig. 6a). In this case, a head releases from MTs under tension and relieves the tension by stepping towards the tethered head.

Bottom Line: Here, by engineering the mechanical and catalytic properties of the motor, we show that dynein processivity minimally requires a single active head and a second inert MT-binding domain.Processivity arises from a high ratio of MT-bound to unbound time, and not from interhead communication.In addition, nucleotide-dependent microtubule release is gated by tension on the linker domain.

View Article: PubMed Central - PubMed

Affiliation: Biophysics Graduate Group, University of California, Berkeley, California 94720, USA.

ABSTRACT
Cytoplasmic dynein is a dimeric motor that transports intracellular cargoes towards the minus end of microtubules (MTs). In contrast to other processive motors, stepping of the dynein motor domains (heads) is not precisely coordinated. Therefore, the mechanism of dynein processivity remains unclear. Here, by engineering the mechanical and catalytic properties of the motor, we show that dynein processivity minimally requires a single active head and a second inert MT-binding domain. Processivity arises from a high ratio of MT-bound to unbound time, and not from interhead communication. In addition, nucleotide-dependent microtubule release is gated by tension on the linker domain. Intramolecular tension sensing is observed in dynein's stepping motion at high interhead separations. On the basis of these results, we propose a quantitative model for the stepping characteristics of dynein and its response to chemical and mechanical perturbation.

Show MeSH
Related in: MedlinePlus