PMID: 17243170

Authors:

Cole DK, Rizkallah PJ, Boulter JM, Sami M, Vuidepot AL, Glick M, Gao F, Bell JI, Jakobsen BK, Gao GF

Title:

Computational design and crystal structure of an enhanced affinity mutant human CD8 alphaalpha coreceptor.

Journal:

Proteins. 2007 Apr 1;67(1):65-74.

Abstract:

Human CD8 is a T cell coreceptor, which binds to pHLA I and plays a pivotal role in the activation of cytotoxic T lymphocytes. Soluble recombinant CD8 alphaalpha has been shown to antagonize T cell activation, both in vitro and in vivo. However, because of a very low affinity for pHLA I, high concentrations of soluble CD8 alphaalpha are required for efficient inhibition. Based upon our knowledge of the wild-type CD8/pHLA I structure, we have designed and produced a mutated form of soluble CD8 alphaalpha that binds to pHLA I with approximately fourfold higher affinity. We have characterized the binding of the high affinity CD8 mutant using surface plasmon resonance and determined its structure at 2.1 A resolution using X-ray crystallography. The analysis of this structure suggests that the higher affinity is achieved by providing a larger side chain that allows for an optimal contact to be made between the HLA alpha3 loop and the mutated CDR-like loops of CD8.