X-ray structure of a human cardiac muscle troponin C/troponin I chimera in two crystal forms

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.

Source: Acta Crystallographica Section F - December 16, 2021 Category: Biochemistry Authors: Yan, C. Sack, J.S. Tags: human cardiac muscle troponin C troponin C/troponin I chimera calcium regulation cardiac muscle contraction research communications Source Type: research