Combinations of affinity-enhancing mutations in a T cell receptor reveal highly nonadditive effects within and between complementarity determining regions and chains
UMass Chan Affiliations
Program in Bioinformatics and Integrative BiologyDepartment of Biochemistry and Molecular Pharmacology
Document Type
Journal ArticlePublication Date
2010-08-24Keywords
Escherichia coliGene Expression
HLA-A2 Antigen
Human T-lymphotropic virus 1
Humans
Kinetics
Models, Molecular
Oligopeptides
*Point Mutation
Protein Binding
Protein Conformation
Receptors, Antigen, T-Cell
Receptors, Antigen, T-Cell, alpha-beta
Biochemistry, Biophysics, and Structural Biology
Computational Biology
Genetic Phenomena
Systems Biology
Metadata
Show full item recordAbstract
Understanding the energetic and structural response to multiple mutations in a protein-protein interface is a key aspect of rational protein design. Here we investigate the cooperativity of combinations of point mutations of a T cell receptor (TCR) that binds in vivo to HLA-A2 MHC and a viral peptide. The mutations were obtained from two sources: a structure-based design study on the TCR alpha chain (nine mutations) and an in vitro selection study on the TCR beta chain (four mutations). In addition to combining the highest-affinity variants from each chain, we tested other combinations of mutations within and among the chains, for a total of 23 TCR mutants that we measured for binding kinetics to the peptide and major histocompatibility complex. A wide range of binding affinities was observed, from 2- to 1000-fold binding improvement versus that of the wild type, with significant nonadditive effects observed within and between TCR chains. This included an amino acid-dependent cooperative interaction between CDR1 and CDR3 residues that are separated by more than 9 A in the wild-type complex. When analyzing the kinetics of the mutations, we found that the association rates were primarily responsible for the cooperativity, while the dissociation rates were responsible for the anticooperativity (less-than-additive energetics). On the basis of structural modeling of anticooperative mutants, we determined that side chain clash between proximal mutants likely led to nonadditive binding energies. These results highlight the complex nature of TCR association and binding and will be informative in future design efforts that combine multiple mutant residues.Source
Biochemistry. 2010 Aug 24;49(33):7050-9. doi: 10.1021/bi901969a. Link to article on publisher's site
DOI
10.1021/bi901969aPermanent Link to this Item
http://hdl.handle.net/20.500.14038/25890PubMed ID
20681514Related Resources
ae974a485f413a2113503eed53cd6c53
10.1021/bi901969a