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Crystal structure of PD-L1 complexed with atezolizumab fab at 2.9A
Structural highlights
FunctionPD1L1_HUMAN Involved in the costimulatory signal, essential for T-cell proliferation and production of IL10 and IFNG, in an IL2-dependent and a PDCD1-independent manner. Interaction with PDCD1 inhibits T-cell proliferation and cytokine production.[1] [2] Publication Abstract from PubMedMonoclonal antibodies targeting PD-1/PD-L1 signaling pathway have achieved unprecedented success in cancer treatment over the last few years. Atezolizumab is the first PD-L1 monoclonal antibody approved by US FDA for cancer therapy; however the molecular basis of atezolizumab in blocking PD-1/PD-L1 interaction is not fully understood. Here we have solved the crystal structure of PD-L1/atezolizumab complex at 2.9 angstrom resolution. The structure shows that atezolizumab binds the front beta-sheet of PD-L1 through three CDR loops from the heavy chain and one CDR loop from the light chain. The binding involves extensive hydrogen-bonding and hydrophobic interactions. Notably there are multiple aromatic residues from the CDR loops forming Pi-Pi stacking or cation-Pi interactions within the center of the binding interface and the buried surface area is more than 2000 A(2), which is the largest amongst all the known PD-L1/antibody structures. Mutagenesis study revealed that two hot-spot residues (E58, R113) of PD-L1 contribute significantly to the binding of atezolizumab. The structure also shows that atezolizumab binds PD-L1 with a distinct heavy and light chain orientation and it blocks PD-1/PD-L1 interaction through competing with PD-1 for the same PD-L1 surface area. Taken together, the complex structure of PD-L1/atezolizumab solved here revealed the molecular mechanism of atezolizumab in immunotherapy and provides basis for future monoclonal antibody optimization and rational design of small chemical compounds targeting PD-L1 surface. Structural basis of the therapeutic anti-PD-L1 antibody atezolizumab.,Zhang F, Qi X, Wang X, Wei D, Wu J, Feng L, Cai H, Wang Y, Zeng N, Xu T, Zhou A, Zheng Y Oncotarget. 2017 Oct 6;8(52):90215-90224. doi: 10.18632/oncotarget.21652., eCollection 2017 Oct 27. PMID:29163822[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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