molecular dynamics of the avian influenza virus
DESCRIPTION
Molecular Dynamics of the Avian Influenza Virus. Team Members: Ashvin Srivatsa , Michael Fu, Ellen Chuang, Ravi Sheth Team Leader: Yuan Zhang. Contents. Influenza Background How Influenza Works Molecular Dynamics Objective Procedure Results Conclusion. Influenza Background. - PowerPoint PPT PresentationTRANSCRIPT
Molecular Dynamics of the Avian Influenza Virus
Team Members: Ashvin Srivatsa, Michael Fu, Ellen Chuang, Ravi Sheth
Team Leader: Yuan Zhang
Contents
• Influenza Background• How Influenza Works• Molecular Dynamics• Objective• Procedure• Results• Conclusion
Influenza Background
The Influenza Problem
• “Flu”• Common viral infection of lungs• Many different strains which mutate regularly• Different levels of virulence• Kills roughly half a million people per year
Historical Flu Pandemics
• 1918 Spanish Flu (H1N1)– 500,000 deaths in U.S.
• 1957 Asian Flu (H2N2)– 69,800 deaths in U.S.
• 1968 Hong Kong Flu (H3N2)– 33,800 deaths in U.S.
Avian Influenza
• H5N1• Form of Influenza A Virus• One of the most virulent strains today, spreads
only from birds to humans• Similar to human “common flu”• Mutates frequently, makes it hard to develop
countermeasures• If a mutation allows for it to spread from human
to human, pandemic would follow
How Influenza Works
Structure of Bird Flu Virus
• Protein Coat– Hemagglutinin – bonds
virus to cell membrane– Neuraminidase – helps
virus reproduce in cell
• Lipid Membrane• RNA
Lifecycle of Bird Flu Virus
• Enters and infects cell
• Reproduce genetic material
• Cell lyses, releasing new viruses
Fusion Peptide
• Part of Hemagglutinin protein• Binds virus to cell membrane
Molecular Dynamics
Molecular Dynamics (MD)
• Involves study of computer simulations that allow molecules and atoms to interact
• Extremely complex, based on physics laws• Must be run on powerful supercomputers
MD Software
• Many different types of software solutions exist
• We utilized VMD and NAMD– VMD – Visual Molecular Dynamics– NAMD2 – Not (just) Another Molecular Dynamics
program
A silicon nanopore, rendered with VMD by the Theoretical and Computational Biophysics Group at
the University of Illinois at Urbana-Champaign
Objective
Objective1. Utilize VMD and NAMD2 to conduct
simulations of the influenza fusion peptide being inserted into a lipid membrane on OSC’s supercomputer clusters
2. Determine how various mutations of the fusion peptide affects its ability to penetrate a lipid membrane
Procedure
Procedure
1. Acquire protein structure files (.pdb) – pdb.org
2. Generate lipid membrane, position protein on membrane
3. Solvate (immerse in water) the protein4. Create batch files that tell supercomputer
what to do
Procedure (Cont.)
5. Perform an equilibration simulation to equilibrate protein
6. Execute simulation that pulls protein into membrane
7. Produce visualization
Results
Fusion Peptide Equilibration (H1N1)
Fusion Peptide Pulling (H1N1)
Fusion Peptide Pulling #2 (H1N1)
Next Step: Mutations
• Random change in genetic material• Changes amino acid structure in proteins• New strains of influenza arise through random
mutations as well as through natural selection
Comparison of Amino Sequences
• Different Strains of the 20 amino acid fusion peptide
• Mutation Names – based on original amino acid, position, and new amino acid
Mutation 1
• Mutation at the “head” of the protein• Variants G1V, G1S– (Changes to Valine, Serine)
• Changes way each peptide enters the membrane (Li, Han, Lai, Bushweller, Cafisso, Tamm)
G1V(green), G1S (red) mutants, H1N1 (orange)
G1V(green), G1S (red) mutants, H1N1 (orange)
Analysis
• The H1N1 maintains a straight structure• G1V, G1S variants bunch up – reduce
efficiency• Shows that the Glycine is important amino
acid on the “head”
Mutation 2
• Mutation near bend in peptide• W14A / H3N2• Boomerang structure is critical to peptide (Lai,
Park, White, Tamm)
W14A(green), H1N1 (blue)
W14A(green), H1N1 (blue)
Analysis
• W14A bunches up, after going in half way, comes back out
• H1N1 maintains structure• Shows that “boomerang” or bend is essential• Also could have contributed the success of the
1918 H1N1 outbreak, compared to H3N2
Mutation 3
• N12G• Affects Boomerang Structure• Chosen by team members (not previously
attempted)
N12G(orange), H1N1 (blue)
N12G(orange), H1N1 (blue)
Analysis
• N12G bunches up halfway through• Does not insert as much as H1N1• Further proves that proper bend is essential
Conclusion
Conclusions
• Boomerang structure of the fusion peptide is essential for proper insertion
• Glycine is essential in the “head” position of the fusion peptide
The Bigger Picture
• The fusion peptide process is a target for drug intervention
• Influenza mutates quickly• Deadly implications if H5N1 mutates to spread
from human to human• Further research is essential to protect
humans from another pandemic
Acknowledgements
Yuan Zhang(project leader)
Barbara Woodall(UNIX)
Elaine Pritchard(Organization)
Brianna, Daniel(Dorm Supervisors)
SI SponsorsParents
VMD(University of Illinois)
NAMD2(University of Illinois)
ClustalW(Amino Acid Alignment)
OSC(Supercomputing Time)
Questions?