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Host-dependent phosphorylation and kinase activity associated with vesicular stomatitis virus
Abstract:
Among the protein kinases associated with vesicular stomatitis virus (VSV), one was identified by immunoprecipitation to be pp60src, the transformation-specific product coded for by avian sarcoma virus, or its endogenous cellular homolog. This activity phosphorylated only tyrosine. pp60src was enriched in the membranes, whereas the serine- and threonine-specific kinases were concentrated with viral cores. The content of pp60src in VSV can be manipulated by growing VSV in different host cells. Monolayer baby hamster kidney cells transformed by an avian sarcoma virus produced VSV progeny which contained 7-fold greater pp60src activity than progeny produced by control untransformed or revertant cells. In contrast, suspension cultures of baby hamster kidney cells which produced VSV with increased tyrosine-specific kinase activity did not affect the content of pp60src. When pp60src was specifically increased in cells, the endogenous phosphorylation of tyrosine residues in the VSV matrix M protein was also enhanced, to as much as 20-fold. The phosphorylation of serine or threonine in this protein or in the other VSV phosphoprotein NS was not affected. Cellular tyrosine-specific kinases other than pp60scr did not change the overall phosphorylation pattern of any VSV phosphoproteins. Experiments designed to test the effects of endogenous phosphorylation on the various functions of the M protein failed to detect any significant alterations.
Insights
Vesicular stomatitis virus (VSV) contains pp60src, a tyrosine kinase. Increasing pp60src activity enhances tyrosine phosphorylation of VSV M protein without altering other functions.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Vesicular stomatitis virus (VSV) is a model system for studying virus-host interactions.
- Protein kinases play crucial roles in viral replication and pathogenesis.
- pp60src is a known tyrosine kinase associated with viral transformation.
Purpose of the Study:
- To identify protein kinases associated with VSV.
- To investigate the role of pp60src in VSV infection and M protein phosphorylation.
- To determine if pp60src activity can be manipulated by host cell conditions.
Main Methods:
- Immunoprecipitation was used to identify protein kinases in VSV.
- Western blotting and kinase assays were performed to quantify pp60src activity.
- VSV was propagated in different host cells to manipulate pp60src content.
Main Results:
- pp60src, a tyrosine-specific kinase, was identified in VSV-associated proteins.
- Growing VSV in transformed baby hamster kidney cells increased pp60src activity by 7-fold.
- Increased pp60src specifically enhanced tyrosine phosphorylation of the VSV M protein up to 20-fold.
Conclusions:
- pp60src is a significant tyrosine kinase associated with VSV.
- The level of pp60src in VSV can be modulated by the host cell environment.
- pp60src-mediated tyrosine phosphorylation of the M protein does not appear to alter its function.