The serum albumin-binding domain of streptococcal protein G is a three-helical bundle: a heteronuclear NMR study.
Streptococcal protein G (SPG) is a cell surface receptor protein with a multiple domain structure containing tandem repeats of serum albumin-binding domains (ABD) and immunoglobulin-binding domains (IgBD). In this paper, we have analysed the fold of ABD. Far-UV circular dichroism analysis of ABD indicates high helical content (56%). Based on an analysis of nuclear magnetic resonance 13C secondary chemical shifts, sequential and short-range NOEs, and a few key nuclear Overhauser effects, we conclude that the ABD is a three-helix bundle. The structure of the ABD is, thus, quite different from the IgBD of protein G [Gronenborn, A.M. et al. (1991) Science 253, 657-661]. This strongly suggests that the ABD and the IgBD of SPG have evolved independently from each other. However, the fold of ABD is similar to that of the IgBD of staphylococcal protein A, possibly indicating a common evolutionary ancestor, despite the lack of sequence homology.
Department of Structural Biochemistry, Pharmacia Biopharmaceuticals, Stockholm, Sweden.
P J
PJ
Kraulis
P
P
Jonasson
P A
PA
Nygren
M
M
Uhlén
L
L
Jendeberg
B
B
Nilsson
J
J
Kördel
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002942:Circular Dichroism; D004269:DNA, Bacterial / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012091:Repetitive Sequences, Nucleic Acid; D012709:Serum Albumin / Q000378:metabolism*; D013205:Staphylococcal Protein A / Q000737:chemistry
D001426:Bacterial Proteins; D004269:DNA, Bacterial; C034284:IgG Fc-binding protein, Streptococcus; D012709:Serum Albumin; D013205:Staphylococcal Protein A