Core mutants of the immunoglobulin binding domain of streptococcal protein G: Stability and structural integrity

FEBS Letters

Frank, M.Kirsten¹  Clore, G.Marius¹  Gronenborn, Angela M.¹ 

[1] Laboratory of Chemical Physics, Building 5, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA

关键词: Protein G;    B1 domain;    Core mutant;    Library;    Protein design;    Structure;    Stability;    GB1;    the B1 immunoglobulin binding domain of streptococcal protein G;    HSQC;    heteronuclear single quantum coherence;    NMR;    nuclear magnetic resonance;    GuHCl;    guanidinium chloride;   

DOI  :  10.1016/S0014-5793(96)01262-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A library of core mutants of the GB1 domain of streptococcal protein G was created, and the structure and stability of selected members was assessed by ¹H-¹⁵N heteronuclear correlation NMR spectroscopy and fluorescence. All mutants comprised changes in β-sheet residues, with sidechains at positions 5 (Leu), 7 (Leu), 52 (Phe) and 54 (Val) forming the β-sheet side of the sheet-helix core interface. A solvent exposed position Ile-6 was chosen as a control. Randomization of bases at codon positions 1 and 3 with thymine at position 2 introduces five possible hydrophobic amino acids, namely Leu, Val, Ile, Phe, and Met. The distribution of encoded amino acids at all five positions is approximately as expected theoretically and indicates that no major bias was introduced towards particular residues. The overall structural integrity of several mutants, as assessed by NMR, ranges from very close to wild type to fully unfolded. Interestingly, the stability of the mutants is not strictly correlated with the number of changes or residue volume.

【 授权许可】

Unknown