1YC8

cAbAn33- Y37V/E44G/R45L triple mutant

Summary for 1YC8

• Entry DOI: 10.2210/pdb1yc8/pdb
• Related: 1YC7
• Descriptor: anti-VSG immunoglobulin heavy chain variable domain cAbAn33 (2 entities in total)
• Functional Keywords: antibody, camel antibody, immune system
• Biological source: Camelus dromedarius (Arabian camel)
• Total number of polymer chains: 2
• Total formula weight: 27230.08

Authors

Conrath, K.,Vincke, C.,Stijlemans, B.,Schymkowitz, J.,Wyns, L.,Muyldermans, S.,Loris, R. (deposition date: 2004-12-22, release date: 2005-06-14, Last modification date: 2023-08-23)

Primary citation

Conrath, K.,Vincke, C.,Stijlemans, B.,Schymkowitz, J.,Decanniere, K.,Wyns, L.,Muyldermans, S.,Loris, R.
Antigen Binding and Solubility Effects upon the Veneering of a Camel VHH in Framework-2 to Mimic a VH.
J.Mol.Biol., 350:112-125, 2005

PubMed Abstract: Heavy chain only antibodies of camelids bind their antigens with a single domain, the VHH, which acquired adaptations relative to classical VHs to function in the absence of a VL partner. Additional CDR loop conformations, outside the canonical loop structures of VHs, broaden the repertoire of the antigen-binding site. The combined effects of part of the CDR3 that folds over the "former" VL binding site and framework-2 mutations to more hydrophilic amino acids, enhance the solubility of VHH domains and prevent VL pairing. cAbAn33, a VHH domain specific for the carbohydrate moiety of the variant surface glycoprotein of trypanosomes, has a short CDR3 loop that does not cover the former VL binding site as well as a VH-specific Trp47 instead of the VHH-specific Gly47. Resurfacing its framework-2 region (mutations Tyr37Val, Glu44Gly and Arg45Leu) to mimic that of a human VH restores the VL binding capacity. In solution, the humanised VHH behaves as a soluble, monomeric entity, albeit with reduced thermodynamic stability and affinity for its antigen. Comparison of the crystal structures of cAbAn33 and its humanised derivative reveals steric hindrance exerted by VHH-specific residues Tyr37 and Arg45 that prevent the VL domain pairing, whereas Glu44 and Arg45 are key elements to avoid insolubility of the domain.

PubMed: 15913651
DOI: 10.1016/j.jmb.2005.04.050

Experimental method

X-RAY DIFFRACTION (2.7 Å)