Solution Structure and Backbone Dynamics of the Defunct Domain of Calcium Vector Protein

• DOI: 10.1021/bi011444q
• Publication Date: 2002-07-26T04:50:13Z
• Authors: Isabelle Théret; Sibyl Baladi; Jos A. Cox; Jacques Gallay; Hiroshi Sakamoto; Constantin T. Cra...
• Keywords: Dynamics

CaVP (calcium vector protein) is a Ca(2+) sensor of the EF-hand protein family which highly abundant in muscle Amphioxus. Its three-dimensional structure not known, but according to sequence analysis, composed two domains, each containing pair motifs. We determined recently solution C-terminal domain (Trp81-Ser161) and characterized large conformational dynamic changes induced by binding. In contrast, N-terminal (Ala1-Asp86) has lost capacity bind metal ion due critical mutations insertions calcium loops. this paper, we report its backbone dynamics based on NMR spectroscopy, nuclear relaxation, molecular modeling. The well-resolved typical motifs, joined together short antiparallel beta-sheet. tertiary arrangement EF-hands results closed-type conformation, with near-antiparallel alpha-helices, similar other pairs absence ions. To characterize internal protein, measured (15)N relaxation rates heteronuclear NOE effect (15)N-labeled N-CaVP at magnetic field 11.74 T 298 K. mainly monomeric undergoes an isotropic Brownian rotational diffusion correlation time 7.1 ns, good agreement fluorescence anisotropy decay measurements. Data analysis using model-free procedure showed that amide groups alpha-helices beta-strands undergo restricted movements picosecond nanosecond scale. binding loops linker fragment also display rapid fluctuations slightly increased amplitudes.