In:
bchm, Walter de Gruyter GmbH, Vol. 394, No. 1 ( 2013-01-01), p. 55-68
Abstract:
Troponin C (TnC) is the Ca 2+ -sensing subunit of troponin that triggers the contraction of striated muscles. In scallops, the striated muscles consume little ATP energy in sustaining strong contractile forces. The N-terminal domain of TnC works as the Ca 2+ sensor in vertebrates, whereas scallop TnC uses the C-terminal domain as the Ca 2+ sensor, suggesting that there are differences in the mechanism of the Ca 2+ -dependent regulation of muscles between invertebrates and vertebrates. Here, we report the crystal structure of Akazara scallop ( Chlamys nipponensis akazara ) adductor muscle TnC C-terminal domain (asTnC C ) complexed with a short troponin I fragment (asTnI S ) and Ca 2+ . The electron density of a Ca 2+ ion is observed in only one of the two EF-hands. The EF-hands of asTnC C can only be in the fully open conformation with the assistance of asTnI S . The number of hydrogen bonds between asTnC C and asTnI S is markedly lower than the number in the vertebrate counterparts. The Ca 2+ modulation on the binding between asTnC C and asTnI S is weaker, but structural change of the complex depending on Ca 2+ concentration was observed. Together, these findings provide a detailed description of the distinct molecular mechanism of contractile regulation in the scallop adductor muscle from that of vertebrates.
Type of Medium:
Online Resource
ISSN:
1437-4315
,
1431-6730
DOI:
10.1515/hsz-2012-0152
Language:
English
Publisher:
Walter de Gruyter GmbH
Publication Date:
2013
detail.hit.zdb_id:
1466062-3
SSG:
12
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