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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Lattice maps of immature and intermediate HIV-1 budding sites.Lattice maps of budding sites. The center and orientation of each aligned subtomogram is marked with a hexagon and is colored according to the cross correlation on a scale from low (red) to high (green). The lattice maps have the threshold set to the same value used for the subtomogram averaging procedure. The lattice map has been superimposed on a slice of 8 nm thickness through the budding viruses. (A) Lattice maps showing two budding particles with the newly reported lattice. (B) Lattice maps showing two budding particles with an immature lattice.
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ppat-1001173-g004: Lattice maps of immature and intermediate HIV-1 budding sites.Lattice maps of budding sites. The center and orientation of each aligned subtomogram is marked with a hexagon and is colored according to the cross correlation on a scale from low (red) to high (green). The lattice maps have the threshold set to the same value used for the subtomogram averaging procedure. The lattice map has been superimposed on a slice of 8 nm thickness through the budding viruses. (A) Lattice maps showing two budding particles with the newly reported lattice. (B) Lattice maps showing two budding particles with an immature lattice.

Mentions: The immature Gag lattice parameters in the budding sites were the same as previously determined for released immature virions [5], [19]: a hexagonal lattice with a lattice constant of 8.0 nm. The lattice maps derived from the budding sites (Fig. 4A) revealed several sites of symmetry breakage, similarly heterogeneous in size and shape as those described for the released virions [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)

Lattice maps of immature and intermediate HIV-1 budding sites.Lattice maps of budding sites. The center and orientation of each aligned subtomogram is marked with a hexagon and is colored according to the cross correlation on a scale from low (red) to high (green). The lattice maps have the threshold set to the same value used for the subtomogram averaging procedure. The lattice map has been superimposed on a slice of 8 nm thickness through the budding viruses. (A) Lattice maps showing two budding particles with the newly reported lattice. (B) Lattice maps showing two budding particles with an immature lattice.
© Copyright Policy
Related In: Results  -  Collection

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

ppat-1001173-g004: Lattice maps of immature and intermediate HIV-1 budding sites.Lattice maps of budding sites. The center and orientation of each aligned subtomogram is marked with a hexagon and is colored according to the cross correlation on a scale from low (red) to high (green). The lattice maps have the threshold set to the same value used for the subtomogram averaging procedure. The lattice map has been superimposed on a slice of 8 nm thickness through the budding viruses. (A) Lattice maps showing two budding particles with the newly reported lattice. (B) Lattice maps showing two budding particles with an immature lattice.
Mentions: The immature Gag lattice parameters in the budding sites were the same as previously determined for released immature virions [5], [19]: a hexagonal lattice with a lattice constant of 8.0 nm. The lattice maps derived from the budding sites (Fig. 4A) revealed several sites of symmetry breakage, similarly heterogeneous in size and shape as those described for the released virions [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
Related in: MedlinePlus