De novo design of antibody complementarity determining regions binding a FLAG tetra-peptide

TitleDe novo design of antibody complementarity determining regions binding a FLAG tetra-peptide
Publication TypeJournal Article
Year of Publication2017
AuthorsEntzminger, KC, Hyun, J-min, Pantazes, RJ, Patterson-Orazem, AC, Qerqez, AN, Frye, ZP, Hughes, RA, Ellington, AD, Lieberman, RL, Maranas, CD, Maynard, JA
JournalSci. Rep.
Volume7
Issue1
Start Page10295
Date Published08/2017
Abstract

Computational antibody engineering efforts to date have focused on improving binding affinities or biophysical characteristics. De novodesign of antibodies binding specific epitopes could greatly accelerate discovery of therapeutics as compared to conventional immunization or synthetic library selection strategies. Here, we employed de novocomplementarity determining region (CDR) design to engineer targeted antibody–antigen interactions using previously described in silicomethods. CDRs predicted to bind the minimal FLAG peptide (Asp–Tyr–Lys–Asp) were grafted onto a single-chain variable fragment (scFv) acceptor framework. Fifty scFvs comprised of designed heavy and light or just heavy chain CDRs were synthesized and screened for peptide binding by phage ELISA. Roughly half of the designs resulted in detectable scFv expression. Four antibodies, designed entirely in silico, bound the minimal FLAG sequence with high specificity and sensitivity. When reformatted as soluble antigen-binding fragments (Fab), these clones expressed well, were predominantly monomeric and retained peptide specificity. In both formats, the antibodies bind the peptide only when present at the amino-terminus of a carrier protein and even conservative peptide amino acid substitutions resulted in a complete loss of binding. These results support in silico CDR design of antibody specificity as an emerging antibody engineering strategy.