Actin filament dynamics in the actomyosin VI complex is regulated allosterically by calcium-calmodulin light chain

Ewa Prochniewicz; Anaëlle Pierre; Brannon R. McCullough; Harvey F. Chin; Wenxiang Cao; Lauren P. Saunders; David D. Thomas; Enrique M. De La Cruz

doi:10.1016/j.jmb.2011.08.058

Actin filament dynamics in the actomyosin VI complex is regulated allosterically by calcium-calmodulin light chain

Ewa Prochniewicz, Anaëlle Pierre, Brannon R. McCullough, Harvey F. Chin, Wenxiang Cao, Lauren P. Saunders, David D. Thomas, Enrique M. De La Cruz

Research output: Contribution to journal › Article › peer-review

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Abstract

The contractile and enzymatic activities of myosin VI are regulated by calcium binding to associated calmodulin (CaM) light chains. We have used transient phosphorescence anisotropy to monitor the microsecond rotational dynamics of erythrosin-iodoacetamide-labeled actin with strongly bound myosin VI (MVI) and to evaluate the effect of MVI-bound CaM light chain on actin filament dynamics. MVI binding lowers the amplitude but accelerates actin filament microsecond dynamics in a Ca²⁺- and CaM-dependent manner, as indicated from an increase in the final anisotropy and a decrease in the correlation time of transient phosphorescence anisotropy decays. MVI with bound apo-CaM or Ca²⁺-CaM weakly affects actin filament microsecond dynamics, relative to other myosins (e.g., muscle myosin II and myosin Va). CaM dissociation from bound MVI damps filament rotational dynamics (i.e., increases the torsional rigidity), such that the perturbation is comparable to that induced by other characterized myosins. Analysis of individual actin filament shape fluctuations imaged by fluorescence microscopy reveals a correlated effect on filament bending mechanics. These data support a model in which Ca ²⁺-dependent CaM binding to the IQ domain of MVI is linked to an allosteric reorganization of the actin binding site(s), which alters the structural dynamics and the mechanical rigidity of actin filaments. Such modulation of filament dynamics may contribute to the Ca² ⁺- and CaM-dependent regulation of myosin VI motility and ATP utilization.

Original language	English (US)
Pages (from-to)	584-592
Number of pages	9
Journal	Journal of Molecular Biology
Volume	413
Issue number	3
DOIs	https://doi.org/10.1016/j.jmb.2011.08.058
State	Published - Oct 28 2011

Bibliographical note

Funding Information:
Phosphorescence experiments were carried out in the Biophysical Spectroscopy Facility, University of Minnesota. The authors thank Octavian Cornea for assistance with preparation of the manuscript. This work was supported by grants from the National Institutes of Health to D.D.T. ( AR32961 , AG26160 ) and to E.M.D.L.C. ( GM071688 , GM071688-S1 , and GM097348 ). E.M.D.L.C. is an American Heart Association Established Investigator ( 0940075N ), a National Science Foundation CAREER Award recipient ( MCB-0546353 ), and a Hellman Family Fellow. B.R.M. was supported by American Heart Association predoctoral award 09PRE2230014 . H.F.C. was supported by National Institutes of Health predoctoral fellowship F31 DC009143 and in part by grants from the American Heart Association ( 0655849T ) and Yale Institute for Nanoscience and Quantum Engineering to E.M.D.L.C.

Keywords

actin
calmodulin
cooperativity
myosin VI
phosphorescence spectroscopy

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title = "Actin filament dynamics in the actomyosin VI complex is regulated allosterically by calcium-calmodulin light chain",

abstract = "The contractile and enzymatic activities of myosin VI are regulated by calcium binding to associated calmodulin (CaM) light chains. We have used transient phosphorescence anisotropy to monitor the microsecond rotational dynamics of erythrosin-iodoacetamide-labeled actin with strongly bound myosin VI (MVI) and to evaluate the effect of MVI-bound CaM light chain on actin filament dynamics. MVI binding lowers the amplitude but accelerates actin filament microsecond dynamics in a Ca2+- and CaM-dependent manner, as indicated from an increase in the final anisotropy and a decrease in the correlation time of transient phosphorescence anisotropy decays. MVI with bound apo-CaM or Ca2+-CaM weakly affects actin filament microsecond dynamics, relative to other myosins (e.g., muscle myosin II and myosin Va). CaM dissociation from bound MVI damps filament rotational dynamics (i.e., increases the torsional rigidity), such that the perturbation is comparable to that induced by other characterized myosins. Analysis of individual actin filament shape fluctuations imaged by fluorescence microscopy reveals a correlated effect on filament bending mechanics. These data support a model in which Ca 2+-dependent CaM binding to the IQ domain of MVI is linked to an allosteric reorganization of the actin binding site(s), which alters the structural dynamics and the mechanical rigidity of actin filaments. Such modulation of filament dynamics may contribute to the Ca2 +- and CaM-dependent regulation of myosin VI motility and ATP utilization.",

keywords = "actin, calmodulin, cooperativity, myosin VI, phosphorescence spectroscopy",

author = "Ewa Prochniewicz and Ana{\"e}lle Pierre and McCullough, {Brannon R.} and Chin, {Harvey F.} and Wenxiang Cao and Saunders, {Lauren P.} and Thomas, {David D.} and {De La Cruz}, {Enrique M.}",

note = "Funding Information: Phosphorescence experiments were carried out in the Biophysical Spectroscopy Facility, University of Minnesota. The authors thank Octavian Cornea for assistance with preparation of the manuscript. This work was supported by grants from the National Institutes of Health to D.D.T. ( AR32961 , AG26160 ) and to E.M.D.L.C. ( GM071688 , GM071688-S1 , and GM097348 ). E.M.D.L.C. is an American Heart Association Established Investigator ( 0940075N ), a National Science Foundation CAREER Award recipient ( MCB-0546353 ), and a Hellman Family Fellow. B.R.M. was supported by American Heart Association predoctoral award 09PRE2230014 . H.F.C. was supported by National Institutes of Health predoctoral fellowship F31 DC009143 and in part by grants from the American Heart Association ( 0655849T ) and Yale Institute for Nanoscience and Quantum Engineering to E.M.D.L.C.",

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doi = "10.1016/j.jmb.2011.08.058",

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T1 - Actin filament dynamics in the actomyosin VI complex is regulated allosterically by calcium-calmodulin light chain

AU - Prochniewicz, Ewa

AU - Pierre, Anaëlle

AU - McCullough, Brannon R.

AU - Chin, Harvey F.

AU - Cao, Wenxiang

AU - Saunders, Lauren P.

AU - Thomas, David D.

AU - De La Cruz, Enrique M.

N1 - Funding Information: Phosphorescence experiments were carried out in the Biophysical Spectroscopy Facility, University of Minnesota. The authors thank Octavian Cornea for assistance with preparation of the manuscript. This work was supported by grants from the National Institutes of Health to D.D.T. ( AR32961 , AG26160 ) and to E.M.D.L.C. ( GM071688 , GM071688-S1 , and GM097348 ). E.M.D.L.C. is an American Heart Association Established Investigator ( 0940075N ), a National Science Foundation CAREER Award recipient ( MCB-0546353 ), and a Hellman Family Fellow. B.R.M. was supported by American Heart Association predoctoral award 09PRE2230014 . H.F.C. was supported by National Institutes of Health predoctoral fellowship F31 DC009143 and in part by grants from the American Heart Association ( 0655849T ) and Yale Institute for Nanoscience and Quantum Engineering to E.M.D.L.C.

PY - 2011/10/28

Y1 - 2011/10/28

N2 - The contractile and enzymatic activities of myosin VI are regulated by calcium binding to associated calmodulin (CaM) light chains. We have used transient phosphorescence anisotropy to monitor the microsecond rotational dynamics of erythrosin-iodoacetamide-labeled actin with strongly bound myosin VI (MVI) and to evaluate the effect of MVI-bound CaM light chain on actin filament dynamics. MVI binding lowers the amplitude but accelerates actin filament microsecond dynamics in a Ca2+- and CaM-dependent manner, as indicated from an increase in the final anisotropy and a decrease in the correlation time of transient phosphorescence anisotropy decays. MVI with bound apo-CaM or Ca2+-CaM weakly affects actin filament microsecond dynamics, relative to other myosins (e.g., muscle myosin II and myosin Va). CaM dissociation from bound MVI damps filament rotational dynamics (i.e., increases the torsional rigidity), such that the perturbation is comparable to that induced by other characterized myosins. Analysis of individual actin filament shape fluctuations imaged by fluorescence microscopy reveals a correlated effect on filament bending mechanics. These data support a model in which Ca 2+-dependent CaM binding to the IQ domain of MVI is linked to an allosteric reorganization of the actin binding site(s), which alters the structural dynamics and the mechanical rigidity of actin filaments. Such modulation of filament dynamics may contribute to the Ca2 +- and CaM-dependent regulation of myosin VI motility and ATP utilization.

AB - The contractile and enzymatic activities of myosin VI are regulated by calcium binding to associated calmodulin (CaM) light chains. We have used transient phosphorescence anisotropy to monitor the microsecond rotational dynamics of erythrosin-iodoacetamide-labeled actin with strongly bound myosin VI (MVI) and to evaluate the effect of MVI-bound CaM light chain on actin filament dynamics. MVI binding lowers the amplitude but accelerates actin filament microsecond dynamics in a Ca2+- and CaM-dependent manner, as indicated from an increase in the final anisotropy and a decrease in the correlation time of transient phosphorescence anisotropy decays. MVI with bound apo-CaM or Ca2+-CaM weakly affects actin filament microsecond dynamics, relative to other myosins (e.g., muscle myosin II and myosin Va). CaM dissociation from bound MVI damps filament rotational dynamics (i.e., increases the torsional rigidity), such that the perturbation is comparable to that induced by other characterized myosins. Analysis of individual actin filament shape fluctuations imaged by fluorescence microscopy reveals a correlated effect on filament bending mechanics. These data support a model in which Ca 2+-dependent CaM binding to the IQ domain of MVI is linked to an allosteric reorganization of the actin binding site(s), which alters the structural dynamics and the mechanical rigidity of actin filaments. Such modulation of filament dynamics may contribute to the Ca2 +- and CaM-dependent regulation of myosin VI motility and ATP utilization.

KW - actin

KW - calmodulin

KW - cooperativity

KW - myosin VI

KW - phosphorescence spectroscopy

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ER -

Actin filament dynamics in the actomyosin VI complex is regulated allosterically by calcium-calmodulin light chain

Abstract

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