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Retrovirus capsid protein assembly arrangements.
Keith Mayo1, Doug Huseby, Jason McDermott
1Vollum Institute and Department of Microbiology MC L220, Oregon Health and Science University, 31814 SW Sam Jackson Park Rd, Portland, OR 97201-3098, USA.
Journal of Molecular Biology
|December 11, 2002
Summary
Retrovirus capsid (CA) proteins form two distinct hexameric arrangements during assembly, switching between forms by altering N-terminal domain contacts. This process mimics viral morphogenesis and provides insights into retrovirus structural protein organization.
Area of Science:
- Structural biology
- Virology
- Biochemistry
Background:
- Retrovirus structural (Gag) proteins assemble into immature and mature forms during particle formation.
- The capsid (CA) protein is crucial for Gag organization, existing as a domain within precursor Gag (PrGag).
- Studying Gag interactions in virions is challenging, leading to in vitro assembly analyses.
Purpose of the Study:
- To investigate the in vitro assembly of human immunodeficiency virus type 1 (HIV-1) and Moloney murine leukemia virus (M-MuLV) capsid (CA) protein variants.
- To characterize the different hexameric arrangements formed by CA proteins.
- To understand the mechanism of switching between assembly forms and its relation to viral morphogenesis.
Main Methods:
- Electron microscope (EM) image reconstruction techniques.
- Analysis of in vitro assembled structures formed by CA variants of HIV-1 and M-MuLV.
Main Results:
- Two distinct hexameric protein arrangements were observed for both HIV-1 and M-MuLV CA variants.
- One arrangement involved hexamers of N-terminal domain (NTD) dimer subunits with shared subunits.
- The second arrangement utilized NTD monomers, lacked subunit sharing, and employed C-terminal domain (CTD) interactions to link hexamers.
Conclusions:
- CA proteins can adopt at least two distinct hexameric configurations.
- Conversion between these forms may involve altering symmetric NTD dimer contacts.
- This dynamic assembly process appears to mimic retroviral morphogenesis.