Myosin X Is a High Duty Ratio Motor*

@article{Homma2005MyosinXI,
  title={Myosin X Is a High Duty Ratio Motor*},
  author={Kazuaki Homma and Mitsuo Ikebe},
  journal={Journal of Biological Chemistry},
  year={2005},
  volume={280},
  pages={29381 - 29391}
}
  • K. Homma, M. Ikebe
  • Published 12 August 2005
  • Biology, Chemistry
  • Journal of Biological Chemistry
Myosin X is expressed in a variety of cell types and plays a role in cargo movement and filopodia extension, but its mechanoenzymatic characteristics are not fully understood. Here we analyzed the kinetic mechanism of the ATP hydrolysis cycle of acto-myosin X using a single-headed construct (M10IQ1). Myosin X was unique for the weak “strong actin binding state” (AMD) with a Kd of 1.6 μm attributed to the large dissociation rate constant (2.1 s-1). Vmax and KATPase of the actin-activated ATPase… 

Myosin Va Becomes a Low Duty Ratio Motor in the Inhibited Form*

TLDR
The present results indicate that M5aFull molecules at a low [Ca2+] is inhibited as a cargo transporter not only due to the decrease in the cross-bridge cycling rate but also due to an increase in the duty ratio thus being dissociated from actin.

Drosophila Myosin VIIA Is a High Duty Ratio Motor with a Unique Kinetic Mechanism*

TLDR
The results suggest that Drosophila myosin VIIA spends the majority of the ATPase cycle in an actomyosin·ADP form, a strong actin binding state, and is classified to be a high duty ratio motor.

Human Myosin Vc Is a Low Duty Ratio Nonprocessive Motor*

TLDR
The kinetic model, based on all kinetic data determined in this study, suggests that myosin Vc spends the majority of the ATPase cycle time in the weak actin binding state in contrast to myosIn Va and Vb.

Kinetic Mechanism of the Fastest Motor Protein, Chara Myosin*

TLDR
Some striking kinetic features of Chara myosin that are suited for the fast movement are revealed: a dramatic acceleration of ADP release by actin (1000-fold) and extremely fast ATP binding rate.

Human Myosin III Is a Motor Having an Extremely High Affinity for Actin*

TLDR
The present results suggest that myosin IIIA can spend a majority of its ATP hydrolysis cycling time on actin, and the kinetic model indicates that both the actin-attached Hydrolysis and the Pi release steps determine the overall cycle rate of the dephosphorylated form.

A Unique ATP Hydrolysis Mechanism of Single-headed Processive Myosin, Myosin IX*

TLDR
It is found that myosin IXb has a rate-limiting ATP hydrolysis step unlike other known myosins, thus populating the prehydrolysis intermediate (M·ATP) and proposing the following model for single-headed processiveMyosin.

Myosin-X: a MyTH-FERM myosin at the tips of filopodia

TLDR
Exciting new studies have begun to reveal the structure and single-molecule properties of this intriguing myosin, as well as its mechanisms of regulation and induction of filopodia.

Phospholipid-dependent regulation of the motor activity of myosin X

TLDR
The following mechanism is proposed: first, the tail inhibits the motor activity of myosin X by intramolecular head-tail interactions to form the folded conformation; second, phospholipid binding reverses the inhibition and disrupts the Folded Conformation, which induces dimer formation, thereby activating the mechanical and cargo transporter activity ofMyosinX.

Myosin-10 produces its power-stroke in two phases and moves processively along a single actin filament under low load

TLDR
The results clarify current controversies about myosin-10 structure and function by revealing that it generates an unexpectedly large biphasic power stroke and moves processively along actin, but detaches rapidly at relatively low force.

References

SHOWING 1-10 OF 41 REFERENCES

Mechanism of Action of Myosin X, a Membrane-associated Molecular Motor*

TLDR
A detailed biochemical kinetic and spectroscopic study on a recombinant myosin X head construct is performed to establish a quantitative model of the enzymatic mechanism of this membrane-boundMyosin, indicating a special mode of actomyosin interaction.

The kinetic mechanism of myosin V.

TLDR
Myosin V is tuned for processive movement on actin and will be capable of transporting cargo at lower motor densities than any other characterized myosin, in that ADP release is the rate-limiting step for the actin-activated ATPase cycle.

The Kinetic Mechanism of Myo1e (Human Myosin-IC)*

TLDR
It is proposed that myo1e is tuned to function in regions of high concentrations of cross-linked actin filaments, while subclass-1 myosin-Is are tuned for rapid sliding, whereas subclass-2 isoforms are tuning for tension maintenance or stress sensing.

Kinetic Mechanism and Regulation of Myosin VI*

TLDR
These measurements are the first to directly measure the steps regulated by HCP for any myosin and propose an alternating site model for the stepping and processivity of two-headed high duty ratio myosins.

A monomeric myosin VI with a large working stroke

TLDR
Using an optical tweezers‐based force transducer, it is found that expressed myosin VI is nonprocessive and produces a large working stroke of 18 nm, difficult to reconcile with the classical ‘lever arm mechanism’, unless other structures in the molecule contribute to the effective lever.

Higher plant myosin XI moves processively on actin with 35 nm steps at high velocity

TLDR
The results indicate that myosin XI is highly specialized for generation of fast processive movement with concomitantly low forces.

The gated gait of the processive molecular motor, myosin V

TLDR
The mechanical interactions between mouse brain myosin V and rabbit skeletal F-actin are measured and it is proposed that the 36-nm steps of the double-headed motor are a combination of the working stroke of the bound head and a biased, thermally driven diffusive movement of the free head onto the next target zone.

Myosin VI is a processive motor with a large step size

TLDR
Here it is shown that myosin VI is also processive by using single molecule motility and optical trapping experiments, and takes much larger steps than expected, based on a simple lever-arm mechanism, for aMyosin with only one light chain in the lever- arm domain.

Direct observation of processive movement by individual myosin V molecules.

TLDR
The maximum speed of the processive movement was 1 microm/s, and the maximum actin-activated ATPase rate was 2.4 s(-1), which apparently imply that BMV travels a great distance, 400 nm, per an ATPase cycle.

Myosin-X provides a motor-based link between integrins and the cytoskeleton

TLDR
Results indicate that Myo10-mediated relocalization of integrins might serve to form adhesive structures and thereby promote filopodial extension.