1j7q
From Proteopedia
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Solution structure and backbone dynamics of the defunct EF-hand domain of Calcium Vector Protein
Overview
CaVP (calcium vector protein) is a Ca(2+) sensor of the EF-hand protein, family which is highly abundant in the muscle of Amphioxus. Its, three-dimensional structure is not known, but according to the sequence, analysis, the protein is composed of two domains, each containing a pair, of EF-hand motifs. We determined recently the solution structure of the, C-terminal domain (Trp81-Ser161) and characterized the large, conformational and dynamic changes induced by Ca(2+) binding. In contrast, the N-terminal domain (Ala1-Asp86) has lost the capacity to bind the metal, ion due to critical mutations and insertions in the two calcium loops. In, this paper, we report the solution structure of the N-terminal domain and, its backbone dynamics based on NMR spectroscopy, nuclear relaxation, and, molecular modeling. The well-resolved three-dimensional structure is, typical of a pair of EF-hand motifs, joined together by a short, antiparallel beta-sheet. The tertiary arrangement of the two EF-hands, results in a closed-type conformation, with near-antiparallel, alpha-helices, similar to other EF-hand pairs in the absence of calcium, ions. To characterize the internal dynamics of the protein, we measured, the (15)N nuclear relaxation rates and the heteronuclear NOE effect in, (15)N-labeled N-CaVP at a magnetic field of 11.74 T and 298 K. The domain, is mainly monomeric in solution and undergoes an isotropic Brownian, rotational diffusion with a correlation time of 7.1 ns, in good agreement, with the fluorescence anisotropy decay measurements. Data analysis using a, model-free procedure showed that the amide backbone groups in the, alpha-helices and beta-strands undergo highly restricted movements on a, picosecond to nanosecond time scale. The amide groups in Ca(2+) binding, loops and in the linker fragment also display rapid fluctuations with, slightly increased amplitudes.
About this Structure
1J7Q is a Single protein structure of sequence from Branchiostoma lanceolatum. Full crystallographic information is available from OCA.
Reference
Solution structure and backbone dynamics of the defunct domain of calcium vector protein., Theret I, Baladi S, Cox JA, Gallay J, Sakamoto H, Craescu CT, Biochemistry. 2001 Nov 20;40(46):13888-97. PMID:11705378
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