Jump to main content
Jump to site search


Role of antibody heavy and light chain interface residues in affinity maturation of binding to HIV envelope glycoprotein

Abstract

The Fv region of an antibody consists of the heavy chain (HC) and light chain (LC) variable domains whose association is maintained by a series of conserved, non-polar interactions. Sequence variation in these interactions allow the HC and LC domains to inhabit a wide range of orientations relative to one another. During chronic infections, somatic mutations are induced, often in the HC /LC interface. We hypothesize that these interface mutations are critical to orient HC and LC for optimal interaction with the antigen and thereby affect binding affinity allosterically. To test this hypothesis, we measured the HC/LC orientation of a set of broad and potent human HIV neutralizing antibodies. The HC/LC interface of these antibodies contained a large numbers of mutations and achieved unusual relative orientations compared to other human antibodies. We expressed and characterized a panel of recombinant HIV CD4 binding site antibodies as the fully matured variant and compared these with variants mutated to the HC/LC interface of the inferred unmutated common ancestor antibody. We found that reverted antibodies have a reduced affinity, suggesting that introduction of mutations in the HC/LC interface was one of the critical steps in achieving high affinity. We then used the ROSETTA software suite to examine the mechanisms through which these mutations affect binding affinity. We determined to what extent the mutations were critical in altering the relative orientation of HC/LC domains to a conformation that is competent to bind the antigen. We further determined whether the mutations excluded alternative HC/LC conformations that would be incompetent to bind the antigen. These findings suggest that somatic mutations in the HC/LC interface, distant from the antigen/antibody contact region, play a critical role in affinity maturation of HIV antibodies by preconfiguring the bound conformation of the antibody in the orientation required for high affinity recognition of the antigen. Thus, optimization of HC/LC interface could serve as an important tool for the optimization of antiviral antibody-antigen binding affinity without altering contact residues.

Back to tab navigation

Supplementary files

Publication details

The article was received on 25 Oct 2018, accepted on 05 Feb 2019 and first published on 08 Feb 2019


Article type: Paper
DOI: 10.1039/C8ME00080H
Citation: Mol. Syst. Des. Eng., 2019, Accepted Manuscript

  •   Request permissions

    Role of antibody heavy and light chain interface residues in affinity maturation of binding to HIV envelope glycoprotein

    A. Cisneros, R. Nargi, E. Parrish, C. Haliburton, J. Meiler and J. Crowe, Mol. Syst. Des. Eng., 2019, Accepted Manuscript , DOI: 10.1039/C8ME00080H

Search articles by author

Spotlight

Advertisements