4r26
Crystal structure of human Fab PGT124, a broadly neutralizing and potent HIV-1 neutralizing antibody
Structural highlights
FunctionIGLC3_HUMAN Constant region of immunoglobulin light chains. Immunoglobulins, also known as antibodies, are membrane-bound or secreted glycoproteins produced by B lymphocytes. In the recognition phase of humoral immunity, the membrane-bound immunoglobulins serve as receptors which, upon binding of a specific antigen, trigger the clonal expansion and differentiation of B lymphocytes into immunoglobulins-secreting plasma cells. Secreted immunoglobulins mediate the effector phase of humoral immunity, which results in the elimination of bound antigens (PubMed:20176268, PubMed:22158414). The antigen binding site is formed by the variable domain of one heavy chain, together with that of its associated light chain. Thus, each immunoglobulin has two antigen binding sites with remarkable affinity for a particular antigen. The variable domains are assembled by a process called V-(D)-J rearrangement and can then be subjected to somatic hypermutations which, after exposure to antigen and selection, allow affinity maturation for a particular antigen (PubMed:17576170, PubMed:20176268).[1] [2] [3] Publication Abstract from PubMedThe HIV envelope glycoprotein (Env) is densely covered with self-glycans that should help shield it from recognition by the human immune system. Here, we examine how a particularly potent family of broadly neutralizing antibodies (Abs) has evolved common and distinct structural features to counter the glycan shield and interact with both glycan and protein components of HIV Env. The inferred germline antibody already harbors potential binding pockets for a glycan and a short protein segment. Affinity maturation then leads to divergent evolutionary branches that either focus on a single glycan and protein segment (e.g., Ab PGT124) or engage multiple glycans (e.g., Abs PGT121-123). Furthermore, other surrounding glycans are avoided by selecting an appropriate initial antibody shape that prevents steric hindrance. Such molecular recognition lessons are important for engineering proteins that can recognize or accommodate glycans. Structural Evolution of Glycan Recognition by a Family of Potent HIV Antibodies.,Garces F, Sok D, Kong L, McBride R, Kim HJ, Saye-Francisco KF, Julien JP, Hua Y, Cupo A, Moore JP, Paulson JC, Ward AB, Burton DR, Wilson IA Cell. 2014 Sep 25;159(1):69-79. doi: 10.1016/j.cell.2014.09.009. PMID:25259921[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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