Chi Seung-Wook, Maeng Cheol-Young, Kim Seung Jun, Oh Mee Sook, Ryu Chun Jeih, Kim Sang Jick, Han Kyou-Hoon, Hong Hyo Jeong, Ryu Seong Eon
Center for Cellular Switch Protein Structure, Molecular Cancer Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-333, Korea.
Proc Natl Acad Sci U S A. 2007 May 29;104(22):9230-5. doi: 10.1073/pnas.0701279104. Epub 2007 May 17.
The humanized monoclonal antibody HzKR127 recognizes the preS1 domain of the human hepatitis B virus surface proteins with a broadly neutralizing activity in vivo. We present the crystal structures of HzKR127 Fab and its complex with a major epitope peptide. In the complex structure, the bound peptide forms a type IV beta-turn followed by 3(10) helical turn, the looped-out conformation of which provides a structural basis for broad neutralization. Upon peptide binding, the antibody undergoes a dramatic complementarity determining region H3 lid opening. To understand the structural implication of the virus neutralization, we carried out comprehensive alanine-scanning mutagenesis of all complementarity determining region residues in HzKR127 Fab. The functional mapping of the antigen-combining site demonstrates the specific roles of major binding determinants in antigen binding, contributing to the rational design for maximal humanization and affinity maturation of the antibody.
人源化单克隆抗体HzKR127可识别乙型肝炎病毒表面蛋白的前S1结构域，在体内具有广泛的中和活性。我们展示了HzKR127 Fab及其与主要表位肽复合物的晶体结构。在复合物结构中，结合的肽形成一个IV型β-转角，随后是3(10)螺旋转角，其环出构象为广泛中和提供了结构基础。肽结合后，抗体的互补决定区H3环发生显著打开。为了解病毒中和的结构意义，我们对HzKR127 Fab中所有互补决定区残基进行了全面的丙氨酸扫描诱变。抗原结合位点的功能图谱显示了主要结合决定簇在抗原结合中的特定作用，有助于抗体最大程度人源化和亲和力成熟的合理设计。
