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Title: | Solution Structures of the C-Terminal Domain of Cardiac Troponin C Free and Bound to the N-Terminal Domain of Cardiac Troponin I | Authors: | Gasmi-Seabrook, Geneviève M. C. Howarth, Jack W. Finley, Natosha Abusamhadneh, Ekram Gaponenko, Vadim Brito, Rui M. M. Solaro, R. John Rosevear, Paul R. |
Issue Date: | 29-Jun-1999 | Publisher: | American Chemical Society | Citation: | Biochemistry. 38:26 (1999) 8313-8322 | Abstract: | The N-terminal domain of cardiac troponin I (cTnI) comprising residues 33−80 and lacking the cardiac-specific amino terminus forms a stable binary complex with the C-terminal domain of cardiac troponin C (cTnC) comprising residues 81−161. We have utilized heteronuclear multidimensional NMR to assign the backbone and side-chain resonances of Ca2+-saturated cTnC(81−161) both free and bound to cTnI(33−80). No significant differences were observed between secondary structural elements determined for free and cTnI(33−80)-bound cTnC(81−161). We have determined solution structures of Ca2+-saturated cTnC(81−161) free and bound to cTnI(33−80). While the tertiary structure of cTnC(81−161) is qualitatively similar to that observed free in solution, the binding of cTnI(33−80) results mainly in an opening of the structure and movement of the loop region between helices F and G. Together, these movements provide the binding site for the N-terminal domain of cTnI. The putative binding site for cTnI(33−80) was determined by mapping amide proton and nitrogen chemical shift changes, induced by the binding of cTnI(33−80), onto the C-terminal cTnC structure. The binding interface for cTnI(33−80), as suggested from chemical shift changes, involves predominantly hydrophobic interactions located in the expanded hydrophobic pocket. The largest chemical shift changes were observed in the loop region connecting helices F and G. Inspection of available TnC sequences reveals that these residues are highly conserved, suggesting a common binding motif for the Ca2+/Mg2+-dependent interaction site in the TnC/TnI complex. | URI: | https://hdl.handle.net/10316/10370 | ISSN: | 0006-2960 | DOI: | 10.1021/bi9902642 | Rights: | openAccess |
Appears in Collections: | FCTUC Química - Artigos em Revistas Internacionais |
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