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Myristylation is involved in intracellular retention of hepatitis B virus envelope proteins
R Prange1, A Clemen, R E Streeck
1Institut für Medizinische Mikrobiologie, Johannes Gutenberg-Universität Mainz, Germany.
Abstract:
The envelope of hepatitis B virus contains three related proteins, one of which is myristylated. The nonmyristylated small and middle protein are assembled into empty envelope particles which are secreted from cells, whereas the myristylated large envelope protein is mainly found in complete virions and is not secreted in the absence of the nucleocapsid. The block to secretion can be partially overcome by mutation or deletion of the myristylation site. Creation of a myristyl attachment site in the small protein impairs the secretion of empty envelope particles but not their intracellular assembly. Myristylation may therefore play a crucial role in hepatitis B virus replication by channeling the envelope proteins into complete viral particles.
Insights
Myristylation of hepatitis B virus (HBV) large envelope protein is crucial for viral replication. This modification directs envelope proteins into complete viral particles, impacting HBV assembly and secretion.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Hepatitis B virus (HBV) envelope proteins are essential for viral structure and assembly.
- Three related envelope proteins exist, with one undergoing myristylation.
- Myristylation is a lipid modification that can influence protein localization and function.
Purpose of the Study:
- To investigate the role of myristylation in hepatitis B virus envelope protein function.
- To determine how myristylation affects the assembly and secretion of HBV envelope proteins.
- To elucidate the mechanism by which myristylation influences HBV replication.
Main Methods:
- Analysis of myristylated and non-myristylated HBV envelope proteins.
- Study of empty envelope particle secretion versus complete virion formation.
- Investigating the effects of myristylation site mutations or deletions on protein secretion and assembly.
- Introducing myristyl attachment sites into small envelope proteins to assess functional impact.
Main Results:
- Non-myristylated small and middle envelope proteins form secreted empty particles.
- Myristylated large envelope protein is primarily in complete virions and not secreted without the nucleocapsid.
- Blocking or removing the myristylation site partially rescues secretion.
- Introducing a myristyl site into the small protein impairs empty particle secretion but not intracellular assembly.
Conclusions:
- Myristylation of hepatitis B virus envelope proteins plays a critical role in viral replication.
- This lipid modification appears to channel envelope proteins into complete viral particles.
- Myristylation influences the fate of envelope proteins, directing them towards virion assembly rather than secretion of empty particles.