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Association of ERK2 mitogen-activated protein kinase with human immunodeficiency virus particles
C Cartier1, M Deckert, C Grangeasse
1INSERM U271, Lyon, France.
Abstract:
Here we report the presence of a protein kinase activity associated with human immunodeficiency virus type 1 (HIV-1) particles. We observed phosphorylation of five major proteins by the endogenous protein kinase activity. Phosphoamino acid analysis revealed phosphorylated serine and threonine residues. In addition, we observed autophosphorylation of two proteins in the presence of gamma-ATP in an in-gel phosphorylation assay. These two proteins are not linked by a disulfide bond, suggesting that two different protein kinases are associated with HIV-1 virions. Our results indicate the presence of ERK2 mitogen-activated protein kinase and of a 53,000-molecular-weight protein kinase associated with virions. Moreover, the use of different HIV strains derived from T cells and promonocytic cells, as well as the use of human T-cell leukemia virus type 1 particles, demonstrates that ERK2 is strongly associated with retrovirus particles in a cell-independent manner. Exogenous substrates, such as histone proteins, and a viral substrate, such as Gag protein, are phosphorylated by virus-associated protein kinases.
Insights
Human immunodeficiency virus type 1 (HIV-1) particles contain protein kinase activity, including ERK2, that phosphorylates viral and exogenous substrates. This kinase association is cell-independent, highlighting a novel aspect of retroviral biology.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Human immunodeficiency virus type 1 (HIV-1) is a retrovirus that infects immune cells.
- The molecular mechanisms underlying HIV-1 replication and virion composition are complex.
- Understanding viral enzyme activities is crucial for developing antiviral strategies.
Purpose of the Study:
- To investigate the presence and nature of protein kinase activity within HIV-1 particles.
- To identify specific protein kinases associated with HIV-1 virions.
- To determine the substrates and cellular independence of these virus-associated kinases.
Main Methods:
- Analysis of protein kinase activity in purified HIV-1 particles.
- Phosphoamino acid analysis to identify phosphorylated residues.
- In-gel phosphorylation assays to detect autophosphorylation.
- Testing kinase activity on exogenous (histone) and viral (Gag) substrates.
- Comparison of kinase association across different HIV strains and with HTLV-1.
Main Results:
- HIV-1 particles possess endogenous protein kinase activity, phosphorylating five major viral proteins.
- Phosphorylation occurs at serine and threonine residues, with evidence of autophosphorylation.
- ERK2 mitogen-activated protein kinase and a 53 kDa protein kinase are identified within virions.
- ERK2 association with retroviral particles is cell-independent, observed in HIV and HTLV-1.
Conclusions:
- HIV-1 virions harbor intrinsic protein kinase activities, including ERK2.
- These virus-associated kinases can phosphorylate both viral proteins (e.g., Gag) and exogenous substrates.
- The cell-independent association of ERK2 with retroviral particles suggests a significant role in the viral lifecycle.