PDBsum entry 1z4x

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Hydrolase PDB id
Protein chain
448 a.a.
Waters ×241

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Key reference
Title Structural studies of the parainfluenza virus 5 hemagglutinin-Neuraminidase tetramer in complex with its receptor, Sialyllactose.
Authors P.Yuan, T.B.Thompson, B.A.Wurzburg, R.G.Paterson, R.A.Lamb, T.S.Jardetzky.
Ref. Structure, 2005, 13, 803-815. [DOI no: 10.1016/j.str.2005.02.019]
PubMed id 15893670
The paramyxovirus hemagglutinin-neuraminidase (HN) functions in virus attachment to cells, cleavage of sialic acid from oligosaccharides, and stimulating membrane fusion during virus entry into cells. The structural basis for these diverse functions remains to be fully understood. We report the crystal structures of the parainfluenza virus 5 (SV5) HN and its complexes with sialic acid, the inhibitor DANA, and the receptor sialyllactose. SV5 HN shares common structural features with HN of Newcastle disease virus (NDV) and human parainfluenza 3 (HPIV3), but unlike the previously determined HN structures, the SV5 HN forms a tetramer in solution, which is thought to be the physiological oligomer. The sialyllactose complex reveals intact receptor within the active site, but no major conformational changes in the protein. The SV5 HN structures do not support previously proposed models for HN action in membrane fusion and suggest alternative mechanisms by which HN may promote virus entry into cells.
Figure 7.
Figure 7. SV5 HN Tetramers
Active sites are marked by space-filling representations of the ligand sialyllactose. The four subunits are shown in different colors.
(A) Top view of the SV5 HN tetramer arrangement.
(B) Side view of the SV5 HN tetramer arrangement, with a 60 packing angle between dimers.
(C) Side view of the superimposed SV5 HN and NDV HN tetramers, showing a shift in dimer packing. SV5 HN is colored blue, and NDV HN is colored green.
(D) A model for HN tetramer rearrangement upon cell-surface receptor binding. The HN tetramer is primarily stabilized by the N-terminal stalk region and can interact with F. Sialic acid receptors are displayed at the cell surface, where binding of the individual HN NA domains could perturb the NA tetramer arrangement, consistent with the weak interactions between NA domains. Changes in the HN NA domain tetramer could affect F interactions and stimulate membrane fusion.
The above figure is reprinted by permission from Cell Press: Structure (2005, 13, 803-815) copyright 2005.
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