X‐ray structure of a human cardiac muscle troponin C/troponin I chimera in two crystal forms. Issue 1 (16th December 2021)

• Record Type: Journal Article
• Authors: Yan, Chunhong; Sack, John S.
• Is Part Of: Acta crystallographica. Volume 78:Issue 1(2022)
• Page Start: 17
• Page End: 24
• Publication Date: 2021-12-16
• Subjects: human cardiac muscle troponin C -- troponin C/troponin I chimera -- calcium regulation -- cardiac muscle contraction; Crystallography -- Periodicals; Crystals -- Periodicals; 548
• DOI: 10.1107/S2053230X21012395
• Languages: English
• ISSNs: 2053-230X

Abstract

Abstract : The X‐ray crystal structure of a human cardiac muscle troponin C/troponin I chimera has been determined in two different crystal forms and shows a conformation of the complex that differs from that previously observed by NMR. In contrast to previous models, the troponin I helix runs in a parallel direction relative to the troponin C groove and completely blocks the calcium desensitizer binding site of the troponin C–troponin I interface. Abstract : The X‐ray crystal structure of a human cardiac muscle troponin C/troponin I chimera has been determined in two different crystal forms and shows a conformation of the complex that differs from that previously observed by NMR. The chimera consists of the N‐terminal domain of troponin C (cTnC; residues 1–80) fused to the switch region of troponin I (cTnI; residues 138–162). In both crystal forms, the cTnI residues form a six‐turn α‐helix that lays across the hydrophobic groove of an adjacent cTnC molecule in the crystal structure. In contrast to previous models, the cTnI helix runs in a parallel direction relative to the cTnC groove and completely blocks the calcium desensitizer binding site of the cTnC–cTnI interface.