A peptide mimic of an antigenic loop of α-human chorionic gonadotropin hormone: solution structure and interaction with a llama VHH domain
- 1 September 2002
- journal article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 366 (2) , 415-422
- https://doi.org/10.1042/bj20020172
Abstract
The X-ray structure of a ternary complex between human chorionic gonadotropin hormone (hCG) and two Fvs recognizing its α and β subunits has been recently determined. The Fvs recognize the elongated hCG molecule by its two ends, one being the Leu-12–Cys-29 loop of the α subunit. We have designed and synthesized a 17-amino-acid peptide (named PepH14) derived from the sequence of this antigenic loop with the purpose of mimicking its three-dimensional structure and its affinity for antibodies. We have determined the solution structure of PepH14 by homonuclear NMR spectroscopy and derived distance restraints. Comparison of this structure with that of the corresponding antigenic loop of α-hCG reveals strong conformational similarities. In particular, the two pairs of residues that establish crucial contacts with the Fv fragment share the same conformation in PepH14 and in the authentic hormone loop. We propose a three-dimensional model of interaction of PepH14 with a llama VHH (VHH-H14) fragment cloned from a single-chain llama immunoglobulin raised against α-hCG. This model has been constrained by the chemical shift variations of the H14 1HN and 15N resonances monitored upon binding with PepH14. Mapping of the backbone chemical shift variations on the VHH structure determined by NMR indicates that PepH14 binds to VHH-H14 and forms a complex using the three complementary determining regions (CDRs). They define a shallow groove encompassing residues Thr-31, Ala-56, Tyr-59 and Trp-104 which have been shown to be in conformational exchange [Renisio, Pérez, Czisch, Guenneugues, Bornet, Frenken, Cambillau and Darbon (2002) Proteins 47, 546–555] and also Phe-37 and Ala-50. This groove is close to the hydrophobic interface area observed between VH and VL domains in Fvs from classical antibodies, which explains the rather lateral binding of PepH14 on the VHH.Keywords
This publication has 21 references indexed in Scilit:
- Solution structure and backbone dynamics of an antigen‐free heavy chain variable domain (VHH) from LlamaProteins-Structure Function and Bioinformatics, 2002
- Lateral recognition of a dye hapten by a llama VHH domainJournal of Molecular Biology, 2001
- Recognition of antigens by single-domain antibody fragments: the superfluous luxury of paired domainsTrends in Biochemical Sciences, 2001
- BiGGER: A new (soft) docking algorithm for predicting protein interactionsProteins-Structure Function and Bioinformatics, 2000
- Crystal structure of a ternary complex between human chorionic gonadotropin (hCG) and two Fv fragments specific for the α and β-subunits 1 1Edited by I. A. WilsonJournal of Molecular Biology, 1999
- Efficient computation of three-dimensional protein structures in solution from nuclear magnetic resonance data using the program DIANA and the supporting programs CALIBA, HABAS and GLOMSAJournal of Molecular Biology, 1991
- Thermal stability of human chorionic gonadotropin. Reversible dissociation of subunits at neutral pH.Journal of Biological Chemistry, 1982
- Glycoprotein Hormones: Structure and FunctionAnnual Review of Biochemistry, 1981
- Human chorionic gonadotropin and ovarian and placental steroidogenesisJournal of Steroid Biochemistry, 1979
- The rates of dissociation and reassociation of the subunits of human chorionic gonadotropinArchives of Biochemistry and Biophysics, 1973