4n1e

Publication Abstract from PubMed

Ancestral protein reconstruction allows the resurrection and characterization of ancient proteins based on computational analyses of sequences of modern-day proteins. Unfortunately, many protein families are highly divergent and not suitable for sequence-based reconstruction approaches. This limitation is exemplified by the antigen receptors of jawed vertebrates (B- and T-cell receptors), heterodimers formed by pairs of Ig domains. These receptors are believed to have evolved from an extinct homodimeric ancestor through a process of gene duplication and diversification; however molecular evidence has so far remained elusive. Here, we use a structural approach and laboratory evolution to reconstruct such molecules and characterize their interaction with antigen. High-resolution crystal structures of reconstructed homodimeric receptors in complex with hen-egg white lysozyme demonstrate how nanomolar affinity binding of asymmetrical antigen is enabled through selective recruitment and structural plasticity within the receptor-binding site. Our results provide structural evidence in support of long-held theories concerning the evolution of antigen receptors, and provide a blueprint for the experimental reconstruction of protein ancestry in the absence of phylogenetic evidence.

Structural reconstruction of protein ancestry.,Rouet R, Langley DB, Schofield P, Christie M, Roome B, Porebski BT, Buckle AM, Clifton BE, Jackson CJ, Stock D, Christ D Proc Natl Acad Sci U S A. 2017 Apr 11;114(15):3897-3902. doi:, 10.1073/pnas.1613477114. Epub 2017 Mar 29. PMID:28356519^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.