Reversible Covalent Binding to Cardiac Troponin C by the Ca2+-Sensitizer Levosimendan

Ian M. Robertson; Sandra E. Pineda-Sanabria; Ziqian Yan; Thomas Kampourakis; Yin-Biao Sun; Brian D. Sykes; Malcolm Irving

doi:10.1021/acs.biochem.6b00758

Reversible Covalent Binding to Cardiac Troponin C by the Ca2+-Sensitizer Levosimendan

Ian M. Robertson, Sandra E. Pineda-Sanabria, Ziqian Yan, Thomas Kampourakis, Yin-Biao Sun, Brian D. Sykes, Malcolm Irving

University of Alberta

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

12 Citations (Scopus)

Abstract

The binding of Ca2+ to cardiac troponin C (cTnC) triggers contraction in heart muscle. In the diseased heart, the
myocardium is often desensitized to Ca2+, which leads to impaired contractility. Therefore, compounds that sensitize cardiac
muscle to Ca2+ (Ca2+-sensitizers) have therapeutic promise. The only Ca2+-sensitizer used regularly in clinical settings is
levosimendan. While the primary target of levosimendan is thought to be cTnC, the molecular details of this interaction are not
well understood. In this study, we used mass spectrometry, computational chemistry, and nuclear magnetic resonance
spectroscopy to demonstrate that levosimendan reacts specifically with cysteine 84 of cTnC to form a reversible thioimidate
bond. We also showed that levosimendan only reacts with the active, Ca2+-bound conformation of cTnC. Finally, we propose a
structural model of levosimendan bound to cTnC, which suggests that the Ca2+-sensitizing function of levosimendan is due to
stabilization of the Ca2+-bound conformation of cTnC.

Original language	English
Pages (from-to)	6032-6045
Number of pages	14
Journal	Biochemistry
Volume	55
Issue number	43
Early online date	27 Sept 2016
DOIs	https://doi.org/10.1021/acs.biochem.6b00758
Publication status	Published - Nov 2016

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10.1021/acs.biochem.6b00758

Cite this

@article{c506c9e4e5be47b29a7cc8781a3cbc97,

title = "Reversible Covalent Binding to Cardiac Troponin C by the Ca2+-Sensitizer Levosimendan",

abstract = "The binding of Ca2+ to cardiac troponin C (cTnC) triggers contraction in heart muscle. In the diseased heart, themyocardium is often desensitized to Ca2+, which leads to impaired contractility. Therefore, compounds that sensitize cardiacmuscle to Ca2+ (Ca2+-sensitizers) have therapeutic promise. The only Ca2+-sensitizer used regularly in clinical settings islevosimendan. While the primary target of levosimendan is thought to be cTnC, the molecular details of this interaction are notwell understood. In this study, we used mass spectrometry, computational chemistry, and nuclear magnetic resonancespectroscopy to demonstrate that levosimendan reacts specifically with cysteine 84 of cTnC to form a reversible thioimidatebond. We also showed that levosimendan only reacts with the active, Ca2+-bound conformation of cTnC. Finally, we propose astructural model of levosimendan bound to cTnC, which suggests that the Ca2+-sensitizing function of levosimendan is due tostabilization of the Ca2+-bound conformation of cTnC.",

author = "Robertson, {Ian M.} and Pineda-Sanabria, {Sandra E.} and Ziqian Yan and Thomas Kampourakis and Yin-Biao Sun and Sykes, {Brian D.} and Malcolm Irving",

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doi = "10.1021/acs.biochem.6b00758",

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T1 - Reversible Covalent Binding to Cardiac Troponin C by the Ca2+-Sensitizer Levosimendan

AU - Robertson, Ian M.

AU - Pineda-Sanabria, Sandra E.

AU - Yan, Ziqian

AU - Kampourakis, Thomas

AU - Sun, Yin-Biao

AU - Sykes, Brian D.

AU - Irving, Malcolm

PY - 2016/11

Y1 - 2016/11

N2 - The binding of Ca2+ to cardiac troponin C (cTnC) triggers contraction in heart muscle. In the diseased heart, themyocardium is often desensitized to Ca2+, which leads to impaired contractility. Therefore, compounds that sensitize cardiacmuscle to Ca2+ (Ca2+-sensitizers) have therapeutic promise. The only Ca2+-sensitizer used regularly in clinical settings islevosimendan. While the primary target of levosimendan is thought to be cTnC, the molecular details of this interaction are notwell understood. In this study, we used mass spectrometry, computational chemistry, and nuclear magnetic resonancespectroscopy to demonstrate that levosimendan reacts specifically with cysteine 84 of cTnC to form a reversible thioimidatebond. We also showed that levosimendan only reacts with the active, Ca2+-bound conformation of cTnC. Finally, we propose astructural model of levosimendan bound to cTnC, which suggests that the Ca2+-sensitizing function of levosimendan is due tostabilization of the Ca2+-bound conformation of cTnC.

AB - The binding of Ca2+ to cardiac troponin C (cTnC) triggers contraction in heart muscle. In the diseased heart, themyocardium is often desensitized to Ca2+, which leads to impaired contractility. Therefore, compounds that sensitize cardiacmuscle to Ca2+ (Ca2+-sensitizers) have therapeutic promise. The only Ca2+-sensitizer used regularly in clinical settings islevosimendan. While the primary target of levosimendan is thought to be cTnC, the molecular details of this interaction are notwell understood. In this study, we used mass spectrometry, computational chemistry, and nuclear magnetic resonancespectroscopy to demonstrate that levosimendan reacts specifically with cysteine 84 of cTnC to form a reversible thioimidatebond. We also showed that levosimendan only reacts with the active, Ca2+-bound conformation of cTnC. Finally, we propose astructural model of levosimendan bound to cTnC, which suggests that the Ca2+-sensitizing function of levosimendan is due tostabilization of the Ca2+-bound conformation of cTnC.

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DO - 10.1021/acs.biochem.6b00758

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