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Creation of a new eye lens crystallin (Gambeta) through structure‐guided mutagenic grafting of the surface of βB2 crystallin onto the hydrophobic core of γB crystallin
Author(s) -
Kapoor Divya,
Singh Balvinder,
Subramanian Karthikeyan,
Guptasarma Purnananda
Publication year - 2009
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2009.07059.x
Subject(s) - crystallin , chemistry , residue (chemistry) , protein engineering , enzyme , rational design , crystallography , stereochemistry , biochemistry , biophysics , materials science , biology , nanotechnology
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, βB2 crystallin and γB crystallin, can be recombined to produce a new protein through rational transplantation of the entire surface of βB2 crystallin upon the structure of γB crystallin, without altering the latter’s interior. This new protein, Gambeta, consists of 61 residues possessing the same identity at structurally equivalent positions in βB2‐ and γB crystallin, 91 surface residues unique to βB2 crystallin, and 27 interior residues unique to γB 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.