Creation of a new eye lens crystallin (Gambeta) through structure-guided mutagenic grafting of the surface of betaB2 crystallin onto the hydrophobic core of gammaB crystallin.
The degree of conservation of three-dimensional folds in protein superfamilies is greater than that of amino acid sequences. Therefore, very different groups of residues (and schemes of residue packing) can be found displayed upon similar structural scaffolds. We have previously demonstrated the workability of a protein engineering-based method for rational mixing of the interior features of an all-beta enzyme with the substrate-binding and catalytic (surface) features of another enzyme whose sequence is not similar but which is structurally homologous to the first enzyme. Here, we extend this method to whole-protein surfaces and interiors. We show how two all-beta Greek key proteins, betaB2 crystallin and gammaB crystallin, can be recombined to produce a new protein through rational transplantation of the entire surface of betaB2 crystallin upon the structure of gammaB crystallin, without altering the latter's interior. This new protein, Gambeta, consists of 61 residues possessing the same identity at structurally equivalent positions in betaB2- and gammaB crystallin, 91 surface residues unique to betaB2 crystallin, and 27 interior residues unique to gammaB crystallin. Gambeta displays a mixture of the structural/biochemical characteristics, surface features and colligative properties of its progenitor crystallins. It also displays optical properties common to both progenitor crystallins (i.e. retention of transparency at high concentrations, as well as high refractivity). The folding of a protein with such a 'patchwork' residue ancestry suggests that interior/surface transplants involving all-beta proteins are a feasible engineering strategy.
Division of Protein Science & Engineering, Institute of Microbial Technology, Chandigarh 160036, Council of Scientific & Industrial Research, New Delhi, India.
Divya
D
Kapoor
Balvinder
B
Singh
Karthikeyan
K
Subramanian
Purnananda
P
Guptasarma
D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D002942:Circular Dichroism; D003459:Crystallins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011485:Protein Binding; D011489:Protein Denaturation; D015202:Protein Engineering / Q000379:methods*; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility; D038206:beta-Crystallin B Chain / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D038222:gamma-Crystallins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D003459:Crystallins; D011994:Recombinant Proteins; D038206:beta-Crystallin B Chain; C113634:beta-crystallin B2; C107738:crystallin, gammaB; C542098:gambeta crystallin; D038222:gamma-Crystallins; D002118:Calcium