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. 2003 Jun 16;22(12):2886-92.
doi: 10.1093/emboj/cdg276.

Three-dimensional structure of the M-MuLV CA protein on a lipid monolayer: a general model for retroviral capsid assembly

Barbie K Ganser  1 , Anchi Cheng, Wesley I Sundquist, Mark Yeager
Affiliations

Three-dimensional structure of the M-MuLV CA protein on a lipid monolayer: a general model for retroviral capsid assembly

Barbie K Ganser et al. EMBO J. .

Abstract

Although retroviruses from different genera form morphologically distinct capsids, we have proposed that all of these structures are composed of similar hexameric arrays of capsid (CA) protein subunits and that their distinct morphologies reflect different distributions of pentameric declinations that allow the structures to close. Consistent with this model, CA proteins from both HIV-1 and Rous sarcoma virus (RSV) form similar hexagonal lattices. However, recent structural studies have suggested that the Moloney murine leukemia virus (M-MuLV) CA protein may assemble differently. We now report an independent three-dimensional reconstruction of two-dimensional crystals of M-MuLV CA. This new reconstruction reveals a hexameric lattice that is similar to those formed by HIV-1 and RSV CA, supporting a generalized model for retroviral capsid assembly.

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Figures

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Fig. 1. Two-dimensional crystals of M-MuLV CA. (A) Single-layer crystals of M-MuLV (His6)-CA on a Ni2+-doped lipid monolayer. (B) Computed Fourier transform of a stained, nominally untilted 2D crystal of M-MuLV CA. (C) Plot of significant reflections identified in (B) following unbending and boxing. The size of the box is proportional to the ratio of the background-subtracted amplitude to the averaged background of the corresponding reflection. Reflections with the highest signal-to-noise ratio are labeled with ‘1–4’. (D) Two-dimensional Fourier-filtered projection image of M-MuLV CA crystals (p1 plane group). Nominally untilted images from the 11 best tilt series were used to calculate the merged projection map.
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Fig. 2. 3D reconstruction of 2D crystals of M-MuLV CA. (A) Comparison of the phases (upper panels) and amplitudes (lower panels) of the (2,0), (2,–2) and (0,2) reflections. These reflections are all at 34.5 Å resolution and should be equivalent for a p6 crystal. (B) Cross-section of the p1 3D map of M-MuLV CA crystals (1 Å thick slab parallel to the membrane). (C) Phases (upper panel) and amplitudes (lower panel) of the (2,0) reflection assuming p6 symmetry. (D) Cross-section of the p6 3D map (1 Å thick slab parallel to the membrane).
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Fig. 3. Phase (upper) and amplitude (lower) variation along the (4,1) and (1,4) lattice lines at 15.1 Å resolution, after merging data from tilted crystals in the two-sided plane group p6.
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Fig. 4. Hexameric assemblies of retroviral CA proteins. Structures of the M-MuLV CA (A) and HIV-1 CA (B) hexamers viewed along the six-fold axes, with the central NTDs (red) oriented toward the viewer and the CTD dimers (yellow) further away. This orientation highlights the similarities between the structures, and the maps are contoured to emphasize the domain organization within the CA molecules. In each case, six NTDs comprise the hexameric rings and six CTDs make dimeric connections to neighboring hexamers (in gray). The size difference between the two structures is probably caused by differences in contouring levels, since other HIV-1 CA helical reconstructions (not shown) have hexamer dimensions similar to the M-MuLV CA hexamer. (C) Slab of the M-MuLV CA hexamer between the white lines in (A), as viewed perpendicular to the lines and parallel to the lipid monolayer (on top in this figure). This view emphasizes the two-domain structure of the CA protein and the CTD dimer linkages that connect the hexamers. (D) Possible model to explain the unit cell polymorphisms found in retroviral CA assemblies. The relative positions of the NTD (red) and CTD (yellow) reflect changes in the flexible linker (orange), which allows the hexamer–hexamer distance to vary while maintaining the same inter- and intra-hexamer interactions.
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References

    1. Barklis E. et al. (1997) Structural analysis of membrane-bound retrovirus capsid proteins. EMBO J., 16, 1199–1213. - PMC - PubMed
    1. Barklis E., McDermott,J., Wilkens,S., Fuller,S. and Thompson,D. (1998) Organization of HIV-1 capsid proteins on a lipid monolayer. J. Biol. Chem., 273, 7177–7180. - PubMed
    1. Berthet-Colominas C., Monaco,S., Novelli,A., Sibaï,G., Mallet,F. and Cusack,S. (1999) Head-to-tail dimers and interdomain flexibility revealed by the crystal structure of HIV-1 capsid protein (p24) complexed with a monoclonal antibody Fab. EMBO J., 18, 1124–1136. - PMC - PubMed
    1. Campbell S. and Vogt,V.M. (1995) Self-assembly in vitro of purified CA–NC proteins from Rous sarcoma virus and human immunodeficiency virus type 1. J. Virol., 69, 6487–6497. - PMC - PubMed
    1. Campos-Olivas R., Newman,J.L. and Summers,M.F. (2000) Solution structure and dynamics of the Rous sarcoma virus capsid protein and comparison with capsid proteins of other retroviruses. J. Mol. Biol., 296, 633–649. - PubMed

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