|Title||Solution NMR structures of IgG binding domains with artificially evolved high levels of sequence identity but different folds.|
|Publication Type||Journal Article|
|Year of Publication||2005|
|Authors||He, Y, Yeh, DCheon, Alexander, P, Bryan, PN, Orban, J|
|Date Published||2005 Nov 1|
|Keywords||Amino Acid Sequence, Binding Sites, Crystallography, X-Ray, Immunoglobulin G, Magnetic Resonance Spectroscopy, Molecular Sequence Data, Mutation, Nerve Tissue Proteins, Protein Folding, Protein Structure, Secondary, Staphylococcal Protein A, Thermodynamics|
We describe here the solution NMR structures of two IgG binding domains with highly homologous sequences but different three-dimensional structures. The proteins, G311 and A219, are derived from the IgG binding domains of their wild-type counterparts, protein G and protein A, respectively. Through a series of site-directed mutations and phage display selections, the sequences of G311 and A219 were designed to converge to a point of high-level sequence identity while keeping their respective wild-type tertiary folds. Structures of both artificially evolved sequences were determined by NMR spectroscopy. The main chain fold of G311 can be superimposed on the wild-type alpha/beta protein G structure with a backbone rmsd of 1.4 A, and the A219 structure can be overlaid on the wild-type three-alpha-helix protein A fold also with a backbone rmsd of 1.4 A. The structure of G311, in particular, accommodates a large number of mutational changes without undergoing a change in the overall fold of the main chain. The structural differences are maintained despite a high level (59%) of sequence identity. These proteins serve as starting points for further experiments that will probe basic concepts of protein folding and conformational switching.
|Grant List||GM62154 / GM / NIGMS NIH HHS / United States|