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PDBsum entry 1skt
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Calcium-binding protein
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PDB id
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1skt
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References listed in PDB file
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Key reference
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Title
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Low-Temperature-Induced structural changes in the apo regulatory domain of skeletal muscle troponin c.
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Authors
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S.Tsuda,
A.Miura,
S.M.Gagné,
L.Spyracopoulos,
B.D.Sykes.
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Ref.
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Biochemistry, 1999,
38,
5693-5700.
[DOI no: ]
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PubMed id
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Abstract
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Contractile activity of skeletal muscle is triggered by a Ca2+-induced "opening"
of the regulatory N-domain of troponin C (apo-NTnC residues 1-90). This
structural transition has become a paradigm for large-scale conformational
changes that affect the interaction between proteins. The regulatory domain is
comprised of two basic structural elements: one contributed by the N-, A-, and
D-helices (NAD unit) and the other by the B- and C-helices (BC unit). The
Ca2+-induced opening is characterized by a movement of the BC unit away from the
NAD unit with a concomitant change in conformation at two hinges (Glu41 and
Val65) of the BC unit. To examine the effect of low temperatures on this
Ca2+-induced structural change and the implications for contractile regulation,
we have examined nuclear magnetic resonance (NMR) spectral changes of apo-NTnC
upon decreasing the temperature from 30 to 4 degrees C. In addition, we have
determined the solution structure of apo-NTnC at 4 degrees C using multinuclear
multidimensional NMR spectroscopy. Decreasing temperatures induce a decrease in
the rates and amplitudes of pico to nanosecond time scale backbone dynamics and
an increase in alpha-helical content for the terminal helices of apo-NTnC. In
addition, chemical shift changes for the Halpha resonances of Val65 and Asp66,
the hinge residues of the BC, unit were observed. Compared to the solution
structure of apo-NTnC determined at 30 degrees C, the BC unit packs more tightly
against the NAD unit in the solution structure determined at 4 degrees C.
Concomitant with the tighter packing of the BC and NAD structural units, a
decrease in the total exposed hydrophobic surface area is observed. The results
have broad implications relative to structure determination of proteins in the
presence of large domain movements, and help to elucidate the relevance of
structures determined under different conditions of physical state and
temperature, reflecting forces ranging from crystal packing to solution dynamics.
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Secondary reference #1
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Title
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Low temperature effect on dynamics of apo n-Domain of troponin c
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Authors
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S.Tsuda,
S.M.Gagne,
L.Spyracopoulos,
B.D.Sykes.
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Ref.
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TO BE PUBLISHED ...
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