2spz
|
STAPHYLOCOCCAL PROTEIN A, Z-DOMAIN, NMR, 10 STRUCTURES
OverviewOverview
Staphylococcal protein A (SpA) is a cell-wall-bound pathogenicity factor, from the bacterium Staphylococcus aureus. Because of their small size and, immunoglobulin (IgG)-binding activities, domains of protein A are targets, for protein engineering efforts and for the development of computational, approaches for de novo protein folding. The NMR solution structure of an, engineered IgG-binding domain of SpA, the Z domain (an analog of the B, domain of SpA), has been determined by simulated annealing with restrained, molecular dynamics on the basis of 671 conformational constraints. The Z, domain contains three well-defined alpha-helices corresponding to, polypeptide segments Lys7 to Leu17 (helix 1), Glu24 to Asp36 (helix 2), and Ser41 to Ala54 (helix 3). A family of ten conformers representing the, solution structure of the Z domain was computed by simulated annealing of, restrained molecular dynamics using the program CONGEN. The average of the, root-mean-square deviations (r.m. s.d.) of the individual NMR conformers, relative to the mean coordinates, for the backbone atoms N, Calpha and C', of residues Phe5 through Ala56 is 0.69 A; the corresponding backbone, r.m.s.d. for the three-helical core is 0.44 A. Helices 1, 2 and 3 are, antiparallel in orientation (Omega12=-170(+/-4) degrees , Omega13=+16(+/-3) degrees , Omega23=+173(+/-7) degrees ). A comparison of, backbone amide hydrogen/deuterium exchange rates in free and IgG-bound Z, domains demonstrates that the amide protons of helices 1, 2 and 3 are, protected from rapid exchange in both states, indicating that all three, helices are also intact in the IgG-bound state. These solution NMR results, differ from the previously determined X-ray structure of the similar SpA B, domain in complex with the Fc fragment of a human IgG antibody, where, helix 3 is not observed in the electron density map and from the solution, NMR structure of the B domain, where helix 3 is observed but helix 1 is, tilted by approximately 30 degrees with respect to helices 2 and 3., Hydrogen-bonded N-cap and C-cap formation is observed for all three, helices of the Z domain; these capping interactions appear to be highly, conserved in the five homologous domains of SpA.
About this StructureAbout this Structure
2SPZ is a Single protein structure of sequence from Staphylococcus aureus. This structure superseeds the now removed PDB entry 1SPZ. Full crystallographic information is available from OCA.
ReferenceReference
High-resolution solution NMR structure of the Z domain of staphylococcal protein A., Tashiro M, Tejero R, Zimmerman DE, Celda B, Nilsson B, Montelione GT, J Mol Biol. 1997 Oct 3;272(4):573-90. PMID:9325113
Page seeded by OCA on Wed Nov 21 14:03:14 2007