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Conformations of the regulatory domain of cardiac troponin C examined by residual dipolar couplings

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Author

  • Kimmo Pääkkönen
  • Tia Sorsa
  • Torbjörn Drakenberg
  • Piero Pollesello
  • Carola Tilgmann
  • Perttu Permi
  • Sami Heikkinen
  • Ilkka Kilpeläinen
  • Arto Annila

Summary, in English

Conformations of the regulatory domain of cardiac troponin C (cNTnC) were studied by means of residual dipolar couplings measured from samples dissolved in dilute liquid crystals. Changes in the main chain HN residual dipolar couplings revealed a conformational change in cNTnC due to the complexation with the second binding region (amino acids 148-163) of cardiac troponin I (cTnI). Formation of the complex is accompanied with a molecular realignment in the liquid crystal. The residual dipolar couplings measured for apo-cNTnC and the complex with TnI were in agreement with the values computed from the corresponding closed and open solution structures, whereas for the calcium-loaded conformation the correlation and quality factor were only modest. Ca2+-cNTnC may be subject to conformational exchange. The data support the model that cardiac troponin C functions as a calcium-dependent open-closed switch, such as the skeletal troponin C.

Publishing year

2000

Language

English

Pages

6665-6672

Publication/Series

European Journal of Biochemistry

Volume

267

Issue

22

Document type

Journal article

Publisher

Wiley-Blackwell

Keywords

  • Calcium-dependent binding
  • Cardiac troponin
  • Conformational exchange
  • NMR
  • Residual dipolar couplings

Status

Published

ISBN/ISSN/Other

  • ISSN: 0014-2956