Limits...
Cryo electron tomography of native HIV-1 budding sites.

Carlson LA, de Marco A, Oberwinkler H, Habermann A, Briggs JA, Kräusslich HG, Grünewald K - PLoS Pathog. (2010)

Bottom Line: Besides the immature lattice, a previously not described Gag lattice was detected in some budding sites and released particles; this lattice was found at high frequencies in a subset of infected T-cells.Buds and released particles carrying this lattice consistently lacked the viral ribonucleoprotein complex, suggesting that they correspond to aberrant products due to premature proteolytic activation.We hypothesize that cellular and/or viral factors normally control the onset of proteolytic maturation during assembly and release, and that this control has been lost in a subset of infected T-cells leading to formation of aberrant particles.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany.

ABSTRACT
The structure of immature and mature HIV-1 particles has been analyzed in detail by cryo electron microscopy, while no such studies have been reported for cellular HIV-1 budding sites. Here, we established a system for studying HIV-1 virus-like particle assembly and release by cryo electron tomography of intact human cells. The lattice of the structural Gag protein in budding sites was indistinguishable from that of the released immature virion, suggesting that its organization is determined at the assembly site without major subsequent rearrangements. Besides the immature lattice, a previously not described Gag lattice was detected in some budding sites and released particles; this lattice was found at high frequencies in a subset of infected T-cells. It displays the same hexagonal symmetry and spacing in the MA-CA layer as the immature lattice, but lacks density corresponding to NC-RNA-p6. Buds and released particles carrying this lattice consistently lacked the viral ribonucleoprotein complex, suggesting that they correspond to aberrant products due to premature proteolytic activation. We hypothesize that cellular and/or viral factors normally control the onset of proteolytic maturation during assembly and release, and that this control has been lost in a subset of infected T-cells leading to formation of aberrant particles.

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Gag unit cell structure in HIV-1 budding sites.Left panels show the average of the aligned subtomograms extracted from an individual budding site with the immature lattice. The right panels show the average from an individual budding site with the newly described lattice. (A) Central radial sections from the structures. Density is white. (B) Isosurface rendering of the structures. A segment of 90° has been cut out to better reveal the internal organization of the lattice. The surfaces have been colored radially to illustrate different domains in Gag: Yellow - membrane + MA; blue/green - CA; grey - NC + RNA. Scale bars 10 nm.
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ppat-1001173-g005: Gag unit cell structure in HIV-1 budding sites.Left panels show the average of the aligned subtomograms extracted from an individual budding site with the immature lattice. The right panels show the average from an individual budding site with the newly described lattice. (A) Central radial sections from the structures. Density is white. (B) Isosurface rendering of the structures. A segment of 90° has been cut out to better reveal the internal organization of the lattice. The surfaces have been colored radially to illustrate different domains in Gag: Yellow - membrane + MA; blue/green - CA; grey - NC + RNA. Scale bars 10 nm.

Mentions: The unit cell structure derived from the cellular tomograms contained density corresponding to the N-terminal and C-terminal domains of CA, respectively, as well as density for the membrane and the NC-RNA layer (Fig. 5A). At the present resolution (roughly 40 Å by the 0.5 Fourier shell correlation criterion), this structure was indistinguishable from that previously reported for released particles [19].


Cryo electron tomography of native HIV-1 budding sites.

Carlson LA, de Marco A, Oberwinkler H, Habermann A, Briggs JA, Kräusslich HG, Grünewald K - PLoS Pathog. (2010)

Gag unit cell structure in HIV-1 budding sites.Left panels show the average of the aligned subtomograms extracted from an individual budding site with the immature lattice. The right panels show the average from an individual budding site with the newly described lattice. (A) Central radial sections from the structures. Density is white. (B) Isosurface rendering of the structures. A segment of 90° has been cut out to better reveal the internal organization of the lattice. The surfaces have been colored radially to illustrate different domains in Gag: Yellow - membrane + MA; blue/green - CA; grey - NC + RNA. Scale bars 10 nm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2991257&req=5

ppat-1001173-g005: Gag unit cell structure in HIV-1 budding sites.Left panels show the average of the aligned subtomograms extracted from an individual budding site with the immature lattice. The right panels show the average from an individual budding site with the newly described lattice. (A) Central radial sections from the structures. Density is white. (B) Isosurface rendering of the structures. A segment of 90° has been cut out to better reveal the internal organization of the lattice. The surfaces have been colored radially to illustrate different domains in Gag: Yellow - membrane + MA; blue/green - CA; grey - NC + RNA. Scale bars 10 nm.
Mentions: The unit cell structure derived from the cellular tomograms contained density corresponding to the N-terminal and C-terminal domains of CA, respectively, as well as density for the membrane and the NC-RNA layer (Fig. 5A). At the present resolution (roughly 40 Å by the 0.5 Fourier shell correlation criterion), this structure was indistinguishable from that previously reported for released particles [19].

Bottom Line: Besides the immature lattice, a previously not described Gag lattice was detected in some budding sites and released particles; this lattice was found at high frequencies in a subset of infected T-cells.Buds and released particles carrying this lattice consistently lacked the viral ribonucleoprotein complex, suggesting that they correspond to aberrant products due to premature proteolytic activation.We hypothesize that cellular and/or viral factors normally control the onset of proteolytic maturation during assembly and release, and that this control has been lost in a subset of infected T-cells leading to formation of aberrant particles.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany.

ABSTRACT
The structure of immature and mature HIV-1 particles has been analyzed in detail by cryo electron microscopy, while no such studies have been reported for cellular HIV-1 budding sites. Here, we established a system for studying HIV-1 virus-like particle assembly and release by cryo electron tomography of intact human cells. The lattice of the structural Gag protein in budding sites was indistinguishable from that of the released immature virion, suggesting that its organization is determined at the assembly site without major subsequent rearrangements. Besides the immature lattice, a previously not described Gag lattice was detected in some budding sites and released particles; this lattice was found at high frequencies in a subset of infected T-cells. It displays the same hexagonal symmetry and spacing in the MA-CA layer as the immature lattice, but lacks density corresponding to NC-RNA-p6. Buds and released particles carrying this lattice consistently lacked the viral ribonucleoprotein complex, suggesting that they correspond to aberrant products due to premature proteolytic activation. We hypothesize that cellular and/or viral factors normally control the onset of proteolytic maturation during assembly and release, and that this control has been lost in a subset of infected T-cells leading to formation of aberrant particles.

Show MeSH