Molecular and Structural Studies of Antibody Diversity Mechanisms

描述（由申请人提供）：抗体分子作为治疗和诊断分子是非常重要的。最近，独特的支架，如骆驼类的VHH，甚至非抗体框架，如“结蛋白”，在生物医学中变得重要起来。哺乳动物的抗体多样性和抗原结合通常局限于免疫球蛋白折叠的CDR环。在挑战这一范式的实验中，我们最近解决了两种含有超长CDR H3s（56和61个氨基酸）的牛抗体的晶体结构，并对超长库进行了深度测序。我们的数据显示，这些CDR H3s形成了一个非常不寻常的结构，由一个长链“柄”组成，它支持一个远离免疫球蛋白表面的富含二硫化物的“旋钮”。有趣的是，这两种不同的抗体含有不同的二硫化物模式，这导致了不同的旋钮结构。Dee测序揭示了超长CDR H3s的广泛多样性，其中旋钮内可能形成多种不同的二硫化物。因此，牛抗体系统可以产生前所未有的巨量CDR H3s，这可能导致令人印象深刻的包含身体产生的二硫化物组合的小折叠的多样性。因此，抗体多样性被定位在一个由免疫球蛋白结构域支持的新小范围内。我们将进行结构、功能和工程研究来研究这种新型抗体的特性，并将这种独特的结构开发成治疗方法。

DESCRIPTION (provided by applicant): Antibody molecules are enormously important as therapeutic and diagnostic molecules. More recently, unique scaffolds like the VHH of camelids, or even non-antibody frameworks like "knottins" have become important in biomedicine. Antibody diversity and antigen binding in mammals is often restricted to the CDR loops of the immunoglobulin fold. In experiments challenging this paradigm, we have recently solved the crystal structures of two bovine antibodies containing ultralong CDR H3s (56 and 61 amino acids) and also deep sequenced the ultralong repertoire. Our data reveal that these CDR H3s form a very unusual architecture composed of a long �-strand "stalk" which supports a disulfide rich "knob" that protrudes far from the immunoglobulin surface. Interestingly, the two different antibodies contain different patterns of disulfides, which result in different knob structures. Dee sequencing reveals extensive diversity in the ultralong CDR H3s where a multitude of different disulfides could potentially form within the knob. Thus, the bovine antibody system can produce an unprecedented repertoire of mega CDR H3s that may result in an impressive diversity of minifolds containing combinations of somatically generated disulfides. Thus, antibody diversity is located in a new minifold supported by the immunoglobulin domain. We will perform structural, functional, and engineering studies to investigate the properties of this new antibody class, as well as to lead the way to developing this unique structure into therapeutics.