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Published on: June 3, 2012
Isolation of matrix protein M1 from influenza viruses by acid-dependent extraction with nonionic detergent
1D.I. Ivanovsky Virology Institute, Moscow, USSR.
Abstract:
Influenza viruses were disrupted layer by layer with the nonionic detergent NP-40 at fixed pH. Treatment of the virions with NP-40 at neutral or mildly alkaline pH (6.8-8.0) yielded viral core structures containing M1 protein. The matrix M1 protein was selectively extracted from cores at acidic pH 3.0-4.5 with citrate, acetate, and phosphate buffers or with morpholinoethanesulfonic acid. The resulting M1 protein sedimented in a glycerol gradient with a coefficient of 2.8 S and most likely existed as a monomeric form of the 27,000-Da polypeptide. An antigenic map of the monomeric protein M1 tested with a panel of monoclonal anti-M1 antibodies was found to be similar to those of the assembled M1 protein in whole virions. The isolated M1 protein retained biological properties and inhibited the RNA polymerase activity of viral RNP. This transcription-inhibition function of M1 monomers was specifically restricted by one of the monoclonal antibodies studied.
Insights
Influenza virus matrix protein M1 was isolated and found to retain its biological function. This M1 protein monomer inhibits viral RNA polymerase activity, a function that can be blocked by specific antibodies.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Influenza viruses are significant human pathogens.
- The matrix protein M1 plays a crucial role in viral structure and assembly.
- Understanding M1 protein function is key to developing antiviral strategies.
Purpose of the Study:
- To isolate and characterize the influenza virus matrix protein M1.
- To investigate the biological properties and functions of M1 protein monomers.
- To explore the interaction of M1 protein with viral ribonucleoprotein (RNP) complexes.
Main Methods:
- Disruption of influenza virions using nonionic detergent NP-40 at controlled pH.
- Selective extraction of M1 protein from viral cores at acidic pH.
- Glycerol gradient sedimentation to determine M1 protein monomeric state.
- Antigenic mapping using monoclonal antibodies.
- Assay of M1 protein's effect on viral RNA polymerase activity.
Main Results:
- Influenza M1 protein was successfully isolated as a monomer (27,000-Da polypeptide) with a sedimentation coefficient of 2.8 S.
- Isolated M1 protein monomers retained biological activity, inhibiting influenza viral RNA polymerase.
- The antigenic profile of M1 monomers was similar to M1 in assembled virions.
- A specific monoclonal antibody was found to restrict the transcription-inhibitory function of M1 monomers.
Conclusions:
- The M1 protein of influenza virus can be isolated in a biologically active monomeric form.
- M1 protein monomers possess the ability to inhibit viral RNA synthesis.
- These findings provide insights into the molecular mechanisms of influenza virus replication and potential therapeutic targets.
