Sequential 1H NMR assignments and secondary structure of the B domain of staphylococcal protein A: structural changes between the free B domain in solution and the Fc-bound B domain in crystal.
The recombinant B domain (FB) of staphylococcal protein A, which specifically binds to the Fc portion of immunoglobulin G (IgG), has been investigated with the use of two-dimensional proton nuclear magnetic resonance spectroscopy. All backbone and side-chain proton resonances of FB (60 amino acid residues), except the amide proton resonance of Ala2, were assigned by the sequential assignment procedures by using double-quantum-filtered correlated spectroscopy (DQF-COSY), homonuclear Hartmann-Hahn spectroscopy (HOHAHA), and nuclear Overhauser enhancement spectroscopy (NOESY). On the basis of the NOESY data, three helical regions, Glu9-His19, Glu25-Asp37, and Ser42-Ala55, were identified in the free FB in solution. Existence of two of the three helical regions, Glu9-His19 and Glu25-Asp37, in consistent with the X-ray crystallographic structure of the Fc-bound FB [Deisenhofer, J. (1981) Biochemistry 20, 2361-2370]. By contrast, in the Fc-bound FB as revealed by the X-ray analysis, the Ser42-Glu48 segment is extended and no structural information has been available in the Ala49-Ala55 segment. We suggest that a significant conformation change is induced in the C-terminal region of FB when it is bound to the Fc portion of IgG.
Torigoe
H
H
Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Shimada
I
I
Saito
A
A
Sato
M
M
Arata
Y
Y
D000595:Amino Acid Sequence; D001665:Binding Sites; D003460:Crystallization; D005813:Genes, Synthetic; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012996:Solutions; D013205:Staphylococcal Protein A / Q000737:chemistry* / Q000378:metabolism
D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D012996:Solutions; D013205:Staphylococcal Protein A