Conserved Asp-137 is important for both structure and regulatory functions of cardiac α-tropomyosin (α-TM) in a novel transgenic mouse model expressing α-TM-D137L

Sumeyye Yar, Shamim A K Chowdhury, Robert T. Davis, Minae Kobayashi, Michelle M. Monasky, Sudarsan Rajan, Beata M. Wolska, Vadim Gaponenko, Tomoyoshi Kobayashi, David F. Wieczorek, R. John Solaro

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

α-Tropomyosin (α-TM) has a conserved, charged Asp-137 residue located in the hydrophobic core of its coiled-coil structure, which is unusual in that the residue is found at a position typically occupied by a hydrophobic residue. Asp-137 is thought to destabilize the coiled-coil and so impart structural flexibility to the molecule, which is believed to be crucial for its function in the heart.Aprevious in vitro study indicated that the conversion of Asp-137 to a more typical canonical Leu alters flexibility of TM and affects its in vitro regulatory functions. However, the physiological importance of the residue Asp-137 and altered TM flexibility is unknown. In this study, we further analyzed structural properties of the α-TM-D137L variant and addressed the physiological importance of TM flexibility in cardiac function in studies with a novel transgenic mouse model expressing α-TM-D137L in the heart. Our NMR spectroscopy data indicated that the presence of D137L introduced long range rearrangements in TM structure. Differential scanning calorimetry measurements demonstrated that α-TM-D137L has higher thermal stability compared with α-TM, which correlated with decreased flexibility. Hearts of transgenic mice expressing α-TM-D137L showed systolic and diastolic dysfunction with decreased myofilament Ca2+ sensitivity and cardiomyocyte contractility without changes in intracellular Ca2+ transients or post-translational modifications of major myofilament proteins. Weconclude that conversion of the highly conserved Asp-137 to Leu results in loss of flexibility of TM that is important for its regulatory functions in mouse hearts. Thus, our results provide insight into the link between flexibility of TM and its function in ejecting hearts.

Original languageEnglish
Pages (from-to)16235-16246
Number of pages12
JournalJournal of Biological Chemistry
Volume288
Issue number23
DOIs
Publication statusPublished - Jun 7 2013

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Tropomyosin
Transgenic Mice
Myofibrils
Differential Scanning Calorimetry
Post Translational Protein Processing
Cardiac Myocytes
Nuclear magnetic resonance spectroscopy
Structural properties
Differential scanning calorimetry
Thermodynamic stability
Magnetic Resonance Spectroscopy
Hot Temperature
Molecules
Proteins

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Conserved Asp-137 is important for both structure and regulatory functions of cardiac α-tropomyosin (α-TM) in a novel transgenic mouse model expressing α-TM-D137L. / Yar, Sumeyye; Chowdhury, Shamim A K; Davis, Robert T.; Kobayashi, Minae; Monasky, Michelle M.; Rajan, Sudarsan; Wolska, Beata M.; Gaponenko, Vadim; Kobayashi, Tomoyoshi; Wieczorek, David F.; Solaro, R. John.

In: Journal of Biological Chemistry, Vol. 288, No. 23, 07.06.2013, p. 16235-16246.

Research output: Contribution to journalArticle

Yar, S, Chowdhury, SAK, Davis, RT, Kobayashi, M, Monasky, MM, Rajan, S, Wolska, BM, Gaponenko, V, Kobayashi, T, Wieczorek, DF & Solaro, RJ 2013, 'Conserved Asp-137 is important for both structure and regulatory functions of cardiac α-tropomyosin (α-TM) in a novel transgenic mouse model expressing α-TM-D137L', Journal of Biological Chemistry, vol. 288, no. 23, pp. 16235-16246. https://doi.org/10.1074/jbc.M113.458695
Yar, Sumeyye ; Chowdhury, Shamim A K ; Davis, Robert T. ; Kobayashi, Minae ; Monasky, Michelle M. ; Rajan, Sudarsan ; Wolska, Beata M. ; Gaponenko, Vadim ; Kobayashi, Tomoyoshi ; Wieczorek, David F. ; Solaro, R. John. / Conserved Asp-137 is important for both structure and regulatory functions of cardiac α-tropomyosin (α-TM) in a novel transgenic mouse model expressing α-TM-D137L. In: Journal of Biological Chemistry. 2013 ; Vol. 288, No. 23. pp. 16235-16246.
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abstract = "α-Tropomyosin (α-TM) has a conserved, charged Asp-137 residue located in the hydrophobic core of its coiled-coil structure, which is unusual in that the residue is found at a position typically occupied by a hydrophobic residue. Asp-137 is thought to destabilize the coiled-coil and so impart structural flexibility to the molecule, which is believed to be crucial for its function in the heart.Aprevious in vitro study indicated that the conversion of Asp-137 to a more typical canonical Leu alters flexibility of TM and affects its in vitro regulatory functions. However, the physiological importance of the residue Asp-137 and altered TM flexibility is unknown. In this study, we further analyzed structural properties of the α-TM-D137L variant and addressed the physiological importance of TM flexibility in cardiac function in studies with a novel transgenic mouse model expressing α-TM-D137L in the heart. Our NMR spectroscopy data indicated that the presence of D137L introduced long range rearrangements in TM structure. Differential scanning calorimetry measurements demonstrated that α-TM-D137L has higher thermal stability compared with α-TM, which correlated with decreased flexibility. Hearts of transgenic mice expressing α-TM-D137L showed systolic and diastolic dysfunction with decreased myofilament Ca2+ sensitivity and cardiomyocyte contractility without changes in intracellular Ca2+ transients or post-translational modifications of major myofilament proteins. Weconclude that conversion of the highly conserved Asp-137 to Leu results in loss of flexibility of TM that is important for its regulatory functions in mouse hearts. Thus, our results provide insight into the link between flexibility of TM and its function in ejecting hearts.",
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T1 - Conserved Asp-137 is important for both structure and regulatory functions of cardiac α-tropomyosin (α-TM) in a novel transgenic mouse model expressing α-TM-D137L

AU - Yar, Sumeyye

AU - Chowdhury, Shamim A K

AU - Davis, Robert T.

AU - Kobayashi, Minae

AU - Monasky, Michelle M.

AU - Rajan, Sudarsan

AU - Wolska, Beata M.

AU - Gaponenko, Vadim

AU - Kobayashi, Tomoyoshi

AU - Wieczorek, David F.

AU - Solaro, R. John

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N2 - α-Tropomyosin (α-TM) has a conserved, charged Asp-137 residue located in the hydrophobic core of its coiled-coil structure, which is unusual in that the residue is found at a position typically occupied by a hydrophobic residue. Asp-137 is thought to destabilize the coiled-coil and so impart structural flexibility to the molecule, which is believed to be crucial for its function in the heart.Aprevious in vitro study indicated that the conversion of Asp-137 to a more typical canonical Leu alters flexibility of TM and affects its in vitro regulatory functions. However, the physiological importance of the residue Asp-137 and altered TM flexibility is unknown. In this study, we further analyzed structural properties of the α-TM-D137L variant and addressed the physiological importance of TM flexibility in cardiac function in studies with a novel transgenic mouse model expressing α-TM-D137L in the heart. Our NMR spectroscopy data indicated that the presence of D137L introduced long range rearrangements in TM structure. Differential scanning calorimetry measurements demonstrated that α-TM-D137L has higher thermal stability compared with α-TM, which correlated with decreased flexibility. Hearts of transgenic mice expressing α-TM-D137L showed systolic and diastolic dysfunction with decreased myofilament Ca2+ sensitivity and cardiomyocyte contractility without changes in intracellular Ca2+ transients or post-translational modifications of major myofilament proteins. Weconclude that conversion of the highly conserved Asp-137 to Leu results in loss of flexibility of TM that is important for its regulatory functions in mouse hearts. Thus, our results provide insight into the link between flexibility of TM and its function in ejecting hearts.

AB - α-Tropomyosin (α-TM) has a conserved, charged Asp-137 residue located in the hydrophobic core of its coiled-coil structure, which is unusual in that the residue is found at a position typically occupied by a hydrophobic residue. Asp-137 is thought to destabilize the coiled-coil and so impart structural flexibility to the molecule, which is believed to be crucial for its function in the heart.Aprevious in vitro study indicated that the conversion of Asp-137 to a more typical canonical Leu alters flexibility of TM and affects its in vitro regulatory functions. However, the physiological importance of the residue Asp-137 and altered TM flexibility is unknown. In this study, we further analyzed structural properties of the α-TM-D137L variant and addressed the physiological importance of TM flexibility in cardiac function in studies with a novel transgenic mouse model expressing α-TM-D137L in the heart. Our NMR spectroscopy data indicated that the presence of D137L introduced long range rearrangements in TM structure. Differential scanning calorimetry measurements demonstrated that α-TM-D137L has higher thermal stability compared with α-TM, which correlated with decreased flexibility. Hearts of transgenic mice expressing α-TM-D137L showed systolic and diastolic dysfunction with decreased myofilament Ca2+ sensitivity and cardiomyocyte contractility without changes in intracellular Ca2+ transients or post-translational modifications of major myofilament proteins. Weconclude that conversion of the highly conserved Asp-137 to Leu results in loss of flexibility of TM that is important for its regulatory functions in mouse hearts. Thus, our results provide insight into the link between flexibility of TM and its function in ejecting hearts.

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