dorsal/arxiv
View SchemaElastic lever arm model for myosin V
| Authors | Andrej Vilfan |
|---|---|
| Categories | |
| ArXiv ID | physics/0503109 |
| URL | https://arxiv.org/abs/physics/0503109 |
| DOI | 10.1529/biophysj.104.046763 |
| Journal | Biophys. J. 88, 3792-3805 (2005) |
Abstract
We present a mechanochemical model for myosin V, a two-headed processive motor protein. We derive the properties of a dimer from those of an individual head, which we model both with a 4-state cycle (detached, attached with ADP.Pi, attached with ADP and attached without nucleotide) and alternatively with a 5-state cycle (where the power stroke is not tightly coupled to the phosphate release). In each state the lever arm leaves the head at a different, but fixed, angle. The lever arm itself is described as an elastic rod. The chemical cycles of both heads are coordinated exclusively by the mechanical connection between the two lever arms. The model explains head coordination by showing that the lead head only binds to actin after the power stroke in the trail head and that it only undergoes its power stroke after the trail head unbinds from actin. Both models (4- and 5-state) reproduce the observed hand-over-hand motion and fit the measured force-velocity relations. The main difference between the two models concerns the load dependence of the run length, which is much weaker in the 5-state model. We show how systematic processivity measurement under varying conditions could be used to distinguish between both models and to determine the kinetic parameters.
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"abstract": "We present a mechanochemical model for myosin V, a two-headed processive\nmotor protein. We derive the properties of a dimer from those of an individual\nhead, which we model both with a 4-state cycle (detached, attached with ADP.Pi,\nattached with ADP and attached without nucleotide) and alternatively with a\n5-state cycle (where the power stroke is not tightly coupled to the phosphate\nrelease). In each state the lever arm leaves the head at a different, but\nfixed, angle. The lever arm itself is described as an elastic rod. The chemical\ncycles of both heads are coordinated exclusively by the mechanical connection\nbetween the two lever arms. The model explains head coordination by showing\nthat the lead head only binds to actin after the power stroke in the trail head\nand that it only undergoes its power stroke after the trail head unbinds from\nactin. Both models (4- and 5-state) reproduce the observed hand-over-hand\nmotion and fit the measured force-velocity relations. The main difference\nbetween the two models concerns the load dependence of the run length, which is\nmuch weaker in the 5-state model. We show how systematic processivity\nmeasurement under varying conditions could be used to distinguish between both\nmodels and to determine the kinetic parameters.",
"arxiv_id": "physics/0503109",
"authors": [
"Andrej Vilfan"
],
"categories": [
"physics.bio-ph",
"cond-mat.soft",
"q-bio.BM"
],
"doi": "10.1529/biophysj.104.046763",
"journal_ref": "Biophys. J. 88, 3792-3805 (2005)",
"title": "Elastic lever arm model for myosin V",
"url": "https://arxiv.org/abs/physics/0503109"
},
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