Global fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.

Kinetic and thermodynamic studies of the mechanochemical cycle of myosin motors are essential for understanding the mechanism of energy conversion. Here, we report our investigation of temperature and free Mg(2+)-ion dependencies of sliding velocities of a high duty ratio class-5 myosin motor, myosi...

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Autores principales:	Igor Chizhov, Falk K Hartmann, Nikolas Hundt, Georgios Tsiavaliaris
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/942434900b3446b3a9d464c708459d43
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spelling	oai:doaj.org-article:942434900b3446b3a9d464c708459d432021-11-18T07:44:20ZGlobal fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.1932-620310.1371/journal.pone.0064797https://doaj.org/article/942434900b3446b3a9d464c708459d432013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23738001/?tool=EBIhttps://doaj.org/toc/1932-6203Kinetic and thermodynamic studies of the mechanochemical cycle of myosin motors are essential for understanding the mechanism of energy conversion. Here, we report our investigation of temperature and free Mg(2+)-ion dependencies of sliding velocities of a high duty ratio class-5 myosin motor, myosin-5b from D. discoideum using in vitro motility assays. Previous studies have shown that the sliding velocity of class-5 myosins obeys modulation by free Mg(2+)-ions. Free Mg(2+)-ions affect ADP release kinetics and the dwell time of actin-attached states. The latter determines the maximal velocity of actin translocation in the sliding filament assay. We measured the temperature dependence of sliding velocity in the range from 5 to 55°C at two limiting free Mg(2+)-ion concentrations. Arrhenius plots demonstrated non-linear behavior. Based on this observation we propose a kinetic model, which explains both sensitivity towards free Mg(2+)-ions and non-linearity of the temperature dependence of sliding velocity. According to this model, velocity is represented as a simple analytical function of temperature and free Mg(2+)-ion concentrations. This function has been applied to global non-linear fit analysis of three data sets including temperature and magnesium (at 20°C) dependence of sliding velocity. As a result we obtain thermodynamic parameters (ΔH(Mg) and ΔS(Mg)) of a fast equilibrium between magnesium free (AM·D) and magnesium bound acto-myosin-ADP (AM· Mg(2+)D) states and the corresponding enthalpic barriers associated with ADP release (ΔH1(‡) and ΔH2(‡)). The herein presented integrative approach of data analysis based on global fitting can be applied to the remaining steps of the acto-myosin ATPase cycle facilitating the determination of energetic parameters and thermodynamics of acto-myosin interactions.Igor ChizhovFalk K HartmannNikolas HundtGeorgios TsiavaliarisPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 8, Iss 5, p e64797 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Igor Chizhov Falk K Hartmann Nikolas Hundt Georgios Tsiavaliaris Global fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.
description	Kinetic and thermodynamic studies of the mechanochemical cycle of myosin motors are essential for understanding the mechanism of energy conversion. Here, we report our investigation of temperature and free Mg(2+)-ion dependencies of sliding velocities of a high duty ratio class-5 myosin motor, myosin-5b from D. discoideum using in vitro motility assays. Previous studies have shown that the sliding velocity of class-5 myosins obeys modulation by free Mg(2+)-ions. Free Mg(2+)-ions affect ADP release kinetics and the dwell time of actin-attached states. The latter determines the maximal velocity of actin translocation in the sliding filament assay. We measured the temperature dependence of sliding velocity in the range from 5 to 55°C at two limiting free Mg(2+)-ion concentrations. Arrhenius plots demonstrated non-linear behavior. Based on this observation we propose a kinetic model, which explains both sensitivity towards free Mg(2+)-ions and non-linearity of the temperature dependence of sliding velocity. According to this model, velocity is represented as a simple analytical function of temperature and free Mg(2+)-ion concentrations. This function has been applied to global non-linear fit analysis of three data sets including temperature and magnesium (at 20°C) dependence of sliding velocity. As a result we obtain thermodynamic parameters (ΔH(Mg) and ΔS(Mg)) of a fast equilibrium between magnesium free (AM·D) and magnesium bound acto-myosin-ADP (AM· Mg(2+)D) states and the corresponding enthalpic barriers associated with ADP release (ΔH1(‡) and ΔH2(‡)). The herein presented integrative approach of data analysis based on global fitting can be applied to the remaining steps of the acto-myosin ATPase cycle facilitating the determination of energetic parameters and thermodynamics of acto-myosin interactions.
format	article
author	Igor Chizhov Falk K Hartmann Nikolas Hundt Georgios Tsiavaliaris
author_facet	Igor Chizhov Falk K Hartmann Nikolas Hundt Georgios Tsiavaliaris
author_sort	Igor Chizhov
title	Global fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.
title_short	Global fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.
title_full	Global fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.
title_fullStr	Global fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.
title_full_unstemmed	Global fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.
title_sort	global fit analysis of myosin-5b motility reveals thermodynamics of mg2+-sensitive acto-myosin-adp states.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/942434900b3446b3a9d464c708459d43
work_keys_str_mv	AT igorchizhov globalfitanalysisofmyosin5bmotilityrevealsthermodynamicsofmg2sensitiveactomyosinadpstates AT falkkhartmann globalfitanalysisofmyosin5bmotilityrevealsthermodynamicsofmg2sensitiveactomyosinadpstates AT nikolashundt globalfitanalysisofmyosin5bmotilityrevealsthermodynamicsofmg2sensitiveactomyosinadpstates AT georgiostsiavaliaris globalfitanalysisofmyosin5bmotilityrevealsthermodynamicsofmg2sensitiveactomyosinadpstates
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Global fit analysis of myosin-5b motility reveals thermodynamics of Mg2+-sensitive acto-myosin-ADP states.

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