Influenza hemagglutinin: Difference between revisions
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[[Image:HA sfp model.jpg|left|thumb|A physical model based on [[5hmg]] from the [http://cbm.msoe.edu/ MSOE Center for BioMolecular Modeling] ]] | |||
[[Influenza hemagglutinin]] (PDB code [[5hmg]]) is one of two proteins found on the surface of an influenza virus. Hemagglutinin plays a key role in both host cell recognition and membrane fusion. | |||
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===Structure=== | ===Structure=== | ||
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The hemagglutinin protein is initially assembled into a homo-trimer. Each of the three identical proteins consists of 549 amino acids. Later during the maturation of the virus, the monomers are cleaved by a protease to generate two chains known as HA1 and HA2. | The hemagglutinin protein is initially assembled into a homo-trimer. Each of the three identical proteins consists of 549 amino acids. Later during the maturation of the virus, the monomers are cleaved by a protease to generate two chains known as HA1 and HA2. | ||
<applet load="5HMG" size="300" color="white" frame="true" align="right" caption="Influenza Hemagglutinin | <applet load="5HMG" size="300" color="white" frame="true" align="right" caption="Glycosylated Influenza Hemagglutinin based on [[5hmg]]" /> | ||
====HA1==== | ====HA1==== | ||
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====HA2==== | ====HA2==== | ||
The <scene name='Influenza_hemagglutinin/Ha2_initial/2'>HA2 protein chain</scene> is primarily | The <scene name='Influenza_hemagglutinin/Ha2_initial/2'>HA2 protein chain</scene> is primarily responsible for facilitating membrane fusion. The C-terminal end of the protein is embedded in the viral membrane. The N-terminal end, known as the <scene name='Influenza_hemagglutinin/Ha2_initial_2/5'>fusion peptide</scene>consists of 10 hydrophobic amino acids. When the protein undergoes pH induced conformational changes, this fusion peptide becomes embedded in the host cell membrane. Additionally, the C-terminus embedded in the viral membrane rearranges, bringing the two membranes closer together and facilitation fusion. | ||
===pH Induced Conformational Changes=== | ===pH Induced Conformational Changes=== | ||
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When the pH level reaches 5.5, the HA1 protein shifts its position, rearranging to allow the HA2 protein to access the endosomal membrane. The HA2 chain begins to rearrange, and the loop shown in blue refolds into a helix at pH5. This causes the HA2 chain to reform into the longest known alpha helix in nature. This allows the fusion peptide to become embedded in the endosomal membrane. The C-terminus of the HA2 also rearranges, positioning the viral membrane in close proximity to the endosomal membrane and allowing membrane fusion to occur. This allows the viral RNA to be released from the capsule and into the host cell cytoplasm. | When the pH level reaches 5.5, the HA1 protein shifts its position, rearranging to allow the HA2 protein to access the endosomal membrane. The HA2 chain begins to rearrange, and the loop shown in blue refolds into a helix at pH5. This causes the HA2 chain to reform into the longest known alpha helix in nature. This allows the fusion peptide to become embedded in the endosomal membrane. The C-terminus of the HA2 also rearranges, positioning the viral membrane in close proximity to the endosomal membrane and allowing membrane fusion to occur. This allows the viral RNA to be released from the capsule and into the host cell cytoplasm. | ||
For schematic diagrame, molecular dynamics simulations, and morph animations that explain '''membrane fusion''' in more detail, see [[SARS-CoV-2 spike protein fusion transformation]]. | |||
===Video=== | ===Video=== | ||
~We hope to have a short video available soon that will display a physical model of this protein and some of the concepts discussed above. | ~We hope to have a short video available soon that will display a physical model of this protein and some of the concepts discussed above. | ||
==<font color = 'red'>MSOE Center for BioMolecular Modeling</font>== | ===3D structures of influenza hemagglutinin=== | ||
[[Hemagglutinin]] | |||
==External Links== | |||
===<font color = 'red'>MSOE Center for BioMolecular Modeling</font>=== | |||
[[Image:Center for BioMolecular Modeling Logo.jpg|left|200px]] | [[Image:Center for BioMolecular Modeling Logo.jpg|left|200px]] | ||
The physical models shown on this page were designed and built by the MSOE Center for BioMolecular Modeling. For more information about physical protein modeling, visit the CBM web site at [http://cbm.msoe.edu/ http://cbm.msoe.edu/] . | The physical models shown on this page were designed and built by the MSOE Center for BioMolecular Modeling. For more information about physical protein modeling, visit the CBM web site at [http://cbm.msoe.edu/ http://cbm.msoe.edu/] . | ||
==Additional Resources== | |||
For additional information, see: [[Influenza]] | |||
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