Epitope mapping and in silico characterization of interactions between Der p 7 allergen and MoAb WH9.
Der p 7 is an important house dust mite allergen. However, antigenic determinants of Der p 7 are largely unknown. The purpose of this study is to analyze the determinants of Der p 7 and determine the structural basis of interactions between Der p 7 and WH9, an IgE-binding inhibition mouse monoclonal antibody (MoAb). IgE and WH9-reactive determinant(s) was identified by immunoblot using allergen mutants. A 3-D binary complex structure of Der p 7 and WH9 was simulated with homology modeling and docking methods. Our results obtained showed that among the five Der p 7 mutants (S156A, I157A, L158A, D159A, P160A), serum no. 1045 with IgE-binding against Der p 7 exhibited a reduced IgE immunoblot reactivity against Der p 7 L158A and D159A mutants. WH9 showed reduced immunoblot reactivity against S156A, L158A, D159A and P160A and the observation was confirmed by immunoblot inhibition. The WH9-binding determinant on Der p 7 containing S156, L158, D159 and P160 assumes a loop-like structure. The structural model of the Der p 7-WH9 complex suggests residues S156, I157, L158, D159 and P160 of Der p 7 contribute to WH9 binding via potential hydrogen bonds, electrostatic and hydrophobic interactions. In conclusion, MoAb WH9 interacts with critical residues L158 and D159 of Der p 7 and inhibits IgE-binding to Der p 7. Results obtained advance our understanding on molecular and structural bases of the antigenicity of Der p 7, its interactions with MoAb WH9 and facilitate the design of safer immunotherapy of human atopic disorders.
Department of Medical Research and Education, Taipei Veterans General Hospital, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Hsiao-Yun
HY
Tai
Jia-Kai
JK
Zhou
Hong
H
Chou
Ming F
MF
Tam
Yu-Sen
YS
Chen
Sheh-Yi
SY
Sheu
Horng-Der
HD
Shen
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism*; D039741:Antigens, Dermatophagoides / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D060829:Arthropod Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D002478:Cells, Cultured; D019295:Computational Biology; D018604:Epitope Mapping / Q000379:methods*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology / Q000378:metabolism; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D060066:Protein Interaction Maps / Q000276:immunology
D000911:Antibodies, Monoclonal; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; C451244:Dermatophagoides pteronyssinus antigen p 7; D007073:Immunoglobulin E