The Dilated Cardiomyopathy G159D Mutation in Cardiac Troponin C Weakens the Anchoring Interaction with Troponin I
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- 作者：Olga K. Baryshnikova ; Ian M. Robertson ; Pascal Mercier ; Brian D. Sykes
- 刊名：Biochemistry
- 出版年：2008
- 出版时间：October 14, 2008
- 年：2008
- 卷：47
- 期：41
- 页码：10950-10960
- 全文大小：458K
- 年卷期：v.47,no.41(October 14, 2008)
- ISSN：1520-4995
文摘
NMR spectroscopy has been employed to elucidate the molecular consequences of the DCM G159D mutation on the structure and dynamics of troponin C, and its interaction with troponin I (TnI). Since the molecular effects of human mutations are often subtle, all NMR experiments were conducted as direct side-by-side comparisons of the wild-type C-domain of troponin C (cCTnC) and the mutant protein, G159D. With the mutation, the affinity toward the anchoring region of cTnI (cTnI34−71) was reduced (KD = 3.0 ± 0.6 μM) compared to that of the wild type (KD < 1 μM). Overall, the structure and dynamics of the G159D·cTnI34−71 complex were very similar to those of the cCTnC·cTnI34−71 complex. There were, however, significant changes in the 1H, 13C, and 15N NMR chemical shifts, especially for the residues in direct contact with cTnI34−71, and the changes in NOE connectivity patterns between the G159D·cTnI34−71 and cCTnC·cTnI34−71 complexes. Thus, the most parsimonious hypothesis is that the development of disease results from the poor anchoring of cTnI to cCTnC, with the resulting increase in the level of acto-myosin inhibition in agreement with physiological data. Another possibility is that long-range electrostatic interactions affect the binding of the inhibitory and switch regions of cTnI (cTnI128−147 and cTnI147−163) and/or the cardiac specific N-terminus of cTnI (cTnI1−29) to the N-domain of cTnC. These important interactions are all spatially close in the X-ray structure of the cardiac TnC core.