VLR Recognition of TLR5 Expands the Molecular Characterization of Protein Antigen Binding by Non-Ig-based Antibodies

• Type of Material: Article
• Authors: Robin J. Gunn, Scripps Research Institute; Brantley R. Herrin, Emory University; Sharmstha Acharya, Scripps Research Institute; Max Dale Cooper, Emory University; Ian A. Wilson, Scripps Research Institute
• Language: English
• Date: 2018-04-27
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2018 Elsevier Ltd
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.jmb.2018.03.016
• Title of Journal or Parent Work: Journal of Molecular Biology
• ISSN: 0022-2836
• Volume: 430
• Issue: 9
• Start Page: 1350
• End Page: 1367
• Grant/Funding Information: The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research; and by the NIH, National Institute of General Medical Sciences (including P41GM103393 and P41GM103694); and the National Cancer Institute (U01CA199882).; This work is supported by NIH grants R01 AI042266 (I.A.W.) and R01 AI072435 (M.D.C.).; Use of the SSRL, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy (DOE) Office of Science, Office of Basic Energy Sciences under Contract no. DE-AC02-76SF00515.; Use of the APS was supported by the DOE, Basic Energy Sciences, Office of Science, under contract no. DE-AC02-06CH11357
• Keywords: innate immunity; MONOCLONAL-ANTIBODIES; leucine-rich repeat; antigen binding; VARIABLE LYMPHOCYTE RECEPTORS; ADAPTIVE IMMUNITY; RHEUMATOID-ARTHRITIS; Science & Technology; SOMATIC DIVERSIFICATION; INNATE IMMUNITY; EVOLUTION; X-ray crystallography; JAWLESS VERTEBRATES; SEA LAMPREY; STRUCTURAL BASIS; Biochemistry & Molecular Biology; protein protein complex; Life Sciences & Biomedicine
• Research Categories: Biology, Molecular; Health Sciences, Immunology

Abstract

Variable lymphocyte receptors (VLRs) are unconventional adaptive immune receptors relatively recently discovered in the phylogenetically ancient jawless vertebrates, lamprey and hagfish. VLRs bind antigens using a leucine-rich repeat fold and are the only known adaptive immune receptors that do not utilize an immunoglobulin fold for antigen recognition. While immunoglobulin antibodies have been studied extensively, there are comparatively few studies on antigen recognition by VLRs, particularly for protein antigens. Here we report isolation, functional and structural characterization of three VLRs that bind the protein toll-like receptor 5 (TLR5) from zebrafish. Two of the VLRs block binding of TLR5 to its cognate ligand flagellin in functional assays using reporter cells. Co-crystal structures revealed that these VLRs bind to two different epitopes on TLR5, both of which include regions involved in flagellin binding. Our work here demonstrates that the lamprey adaptive immune system can be used to generate high-affinity VLR clones that recognize different epitopes and differentially impact natural ligand binding to a protein antigen.