1J7Q

Solution structure and backbone dynamics of the defunct EF-hand domain of Calcium Vector Protein

Summary for 1J7Q

• Entry DOI: 10.2210/pdb1j7q/pdb
• Descriptor: Calcium Vector Protein (1 entity in total)
• Functional Keywords: ef-hand family, calcium binding protein, metal binding protein
• Biological source: Branchiostoma lanceolatum (amphioxus)
• Cellular location: Cytoplasm: P04573
• Total number of polymer chains: 1
• Total formula weight: 9788.16

Authors

Theret, I.,Baladi, S.,Cox, J.A.,Gallay, J.,Sakamoto, H.,Craescu, C.T. (deposition date: 2001-05-18, release date: 2001-06-06, Last modification date: 2024-05-22)

Primary citation

Theret, I.,Baladi, S.,Cox, J.A.,Gallay, J.,Sakamoto, H.,Craescu, C.T.
Solution structure and backbone dynamics of the defunct domain of calcium vector protein.
Biochemistry, 40:13888-13897, 2001

PubMed Abstract: 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.

PubMed: 11705378
DOI: 10.1021/bi011444q

Experimental method

SOLUTION NMR