Sequence-specific 1H NMR assignments and secondary structure of the streptococcal protein G B2-domain.
Two-dimensional NMR spectroscopy has been used to obtain sequence-specific 1H NMR assignments for the IgG-binding B2-domain of streptococcal protein G. Secondary structure elements were identified from analysis of characteristic backbone-backbone NOE patterns and amide proton exchange data. The B2-domain contains a four-stranded beta-sheet region in which the two inner strands form a parallel beta-sheet with each other and antiparallel beta-sheets with the outer strands. The outer strands are connected via a 16-residue alpha-helix and short loops on both ends of the helix. The alpha-helix and beta-sheet structures contain well-defined polar and apolar sides, and numerous long-range NOEs from the apolar helix to apolar sheet regions were used to derive a model for the global fold of the B2-domain. While the overall fold is similar to that obtained for B1-type domains, differences in amide proton exchange rates and hydrophobic packing are observed.
Orban
J
J
Center for Advanced Research in Biotechnology, University of Maryland, Rockville 20850.
Alexander
P
P
Bryan
P
P
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007074:Immunoglobulin G / Q000235:genetics / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011522:Protons
D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007074:Immunoglobulin G; D011522:Protons