National Center for
5ACO: Cryo-em Structure Of Pgt128 Fab In Complex With Bg505 Sosip. 664 Env Trimer
Model Building and Refinement of a Natively Glycosylated HIV-1 Env Protein by High-Resolution Cryoelectron Microscopy
Structure (2015) 23 p.1943-1951
Secretory and membrane proteins from mammalian cells undergo post-translational modifications, including N-linked glycosylation, which can result in a large number of possible glycoforms. This sample heterogeneity can be problematic for structural studies, particularly X-ray crystallography. Thus, crystal structures of heavily glycosylated proteins such as the HIV-1 Env viral spike protein have been determined by removing the majority of glycans. This step is most frequently carried out using Endoglycosidase H (EndoH) and requires that all expressed glycans be in the high-mannose form, which is often not the native glycoform. With significantly improved technologies in single-particle cryoelectron microscopy, we demonstrate that it is now possible to refine and build natively glycosylated HIV-1 Env structures in solution to 4.36 A resolution. At this resolution we can now analyze the complete epitope of a broadly neutralizing antibody (bnAb), PGT128, in the context of the trimer expressed with native glycans.
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