A Rational Engineering Strategy for Designing Protein A-Binding Camelid Single-Domain Antibodies

Staphylococcal protein A (SpA) and streptococcal protein G (SpG) affinity chromatography are the gold standards for purifying monoclonal antibodies (mAbs) in therapeutic applications. However, camelid VHH single-domain Abs (sdAbs or VHHs) are not bound by SpG and only sporadically bound by SpA. Curr...

Full description

Saved in:
Bibliographic Details
Published in:PloS one 2016-09, Vol.11 (9), p.e0163113
Main Authors: Henry, Kevin A, Sulea, Traian, van Faassen, Henk, Hussack, Greg, Purisima, Enrico O, MacKenzie, C Roger, Arbabi-Ghahroudi, Mehdi
Format: Article
Language:English
Subjects:
Affinity
Affinity chromatography
Animals
Antigens
Binding
Bioinformatics
Biology and Life Sciences
Camelids, New World - immunology
Cancer
Chromatography
Councils
Environmental science
Frequency variation
Genes
Health aspects
Immunoglobulins
Immunological tolerance
Medicine and Health Sciences
Monoclonal antibodies
Mutagenesis
Mutation
Nanobodies
Physical Sciences
Protein A
Protein binding
Protein Engineering
Protein G
Proteins
Purification
Research and analysis methods
Single-Domain Antibodies - genetics
Staphylococcal Protein A - genetics
Streptococcal protein G
Streptococcus
Therapeutic applications
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Staphylococcal protein A (SpA) and streptococcal protein G (SpG) affinity chromatography are the gold standards for purifying monoclonal antibodies (mAbs) in therapeutic applications. However, camelid VHH single-domain Abs (sdAbs or VHHs) are not bound by SpG and only sporadically bound by SpA. Currently, VHHs require affinity tag-based purification, which limits their therapeutic potential and adds considerable complexity and cost to their production. Here we describe a simple and rapid mutagenesis-based approach designed to confer SpA binding upon a priori non-SpA-binding VHHs. We show that SpA binding of VHHs is determined primarily by the same set of residues as in human mAbs, albeit with an unexpected degree of tolerance to substitutions at certain core and non-core positions and some limited dependence on at least one residue outside the SpA interface, and that SpA binding could be successfully introduced into five VHHs against three different targets with no adverse effects on expression yield or antigen binding. Next-generation sequencing of llama, alpaca and dromedary VHH repertoires suggested that species differences in SpA binding may result from frequency variation in specific deleterious polymorphisms, especially Ile57. Thus, the SpA binding phenotype of camelid VHHs can be easily modulated to take advantage of tag-less purification techniques, although the frequency with which this is required may depend on the source species.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0163113