Interaction of levosimendan with cardiac troponin C in the presence of cardiac troponin I peptides.

Article Details

Citation

Copy to clipboard

Sorsa T, Pollesello P, Permi P, Drakenberg T, Kilpelainen I

Interaction of levosimendan with cardiac troponin C in the presence of cardiac troponin I peptides.

J Mol Cell Cardiol. 2003 Sep;35(9):1055-61.

PubMed ID

12967628 [ View in PubMed

]

Abstract

The interaction between troponin C (TnC) and troponin I (TnI) is essential for the regulation of muscle contraction. There are several binding sites for TnI on TnC that are differentially occupied depending on the phase of the contraction/relaxation cycle. TnI and TnC interact in an antiparallel fashion with each other. The C-domain of cTnC and the N-domain region of cTnI(residues 33-70) always interact under physiological conditions, whereas the interaction between regulatory regions of TnC and TnI (residues 128-166) is calcium dependent. Previously, it has been shown that levosimendan, a calcium sensitizer used as a treatment for acute heart failure, can interact with both domains of isolated cTnC. To understand which interaction is relevant for the mechanism of calcium sensitization, we used a more complete troponin model obtained by complexing cTnI(32-79) and cTnI(128-180) with calcium-saturated cTnC(CS). The cTnI peptides bound to cTnC(CS) to form a 1:1:1 complex. The interaction of levosimendan with this complex was followed by 1H-(15)N heteronuclear correlation spectroscopy. It was clear that based on chemical shift changes, cTnI(32-79) blocked the levosimendan interaction sites on the C-domain, whereas cTnI(128-180) did not compete with levosimendan for the binding site on the N-domain. Hence, the effective binding site of levosimendan on cTnC resulting in the calcium-sensitizing effect is located in the regulatory domain (N-domain).

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Levosimendan	Troponin C, slow skeletal and cardiac muscles	Protein	Humans	Yes	Potentiator	Details