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Cyclophilin A interacts with diverse lentiviral capsids.

Lin TY, Emerman M - Retrovirology (2006)

Bottom Line: This binding positively affects some early stage of the viral life-cycle because prevention of binding either by drugs that occupy that active site of cyclophilin A, by mutation in HIV-1 CA, or RNAi that knocks down intracellular CypA level diminishes viral infectivity.We find that diverse lentiviruses, FIV and SIVagmTAN also bind to CypA.Mutagenesis of FIV CA showed that an amino acid that is in a homologous position to the proline at amino acid 90 of HIV-1 CA is essential for FIV interactions with CypA.

View Article: PubMed Central - HTML - PubMed

Affiliation: Pathobiology Graduate Program, University of Washington, Seattle, WA 98195, USA. linty@u.washington.edu

ABSTRACT

Background: The capsid (CA) protein of HIV-1 binds with high affinity to the host protein cyclophilin A (CypA). This binding positively affects some early stage of the viral life-cycle because prevention of binding either by drugs that occupy that active site of cyclophilin A, by mutation in HIV-1 CA, or RNAi that knocks down intracellular CypA level diminishes viral infectivity. The closely related lentivirus, SIVcpz also binds CypA, but it was thought that this interaction was limited to the HIV-1/SIVcpz lineage because other retroviruses failed to interact with CypA in a yeast two-hybrid assay.

Results: We find that diverse lentiviruses, FIV and SIVagmTAN also bind to CypA. Mutagenesis of FIV CA showed that an amino acid that is in a homologous position to the proline at amino acid 90 of HIV-1 CA is essential for FIV interactions with CypA.

Conclusion: These results demonstrate that CypA binding to lentiviruses is more widespread than previously thought and suggest that this interaction is evolutionarily important for lentiviral infection.

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The CypA-dependency of FIV. Jurkat T cells were infected with HIV-1 wild-type (A), FIV wild-type (B), and FIV P90A (C) in the presence or absence of 1.25 μM of CsA. All viruses were first normalized on CRFK cells and equivalent CRFK infectious units were used and are plotted on the X-axis. For example, the amount of virus that gave 20% GFP positive cells on CRFK cells is 0.2 on the X-axis. The infected Jurkat cells were analyzed by flow cytometry and the infectivity is presented as % GFP+ cells.
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Figure 4: The CypA-dependency of FIV. Jurkat T cells were infected with HIV-1 wild-type (A), FIV wild-type (B), and FIV P90A (C) in the presence or absence of 1.25 μM of CsA. All viruses were first normalized on CRFK cells and equivalent CRFK infectious units were used and are plotted on the X-axis. For example, the amount of virus that gave 20% GFP positive cells on CRFK cells is 0.2 on the X-axis. The infected Jurkat cells were analyzed by flow cytometry and the infectivity is presented as % GFP+ cells.

Mentions: Previous reports showed that CsA decreases spreading infections of FIV in cells and in animals [24,25]. However, comparisons with HIV-1 were not done. It has been shown that the infectivity of HIV-1 drops 2–5 fold when the CypA/CA interaction is blocked by CsA in Jurkat T cells in single-cycle infection experiments [7-9]. To examine the role of CypA in FIV infection in the same cell type, Jurkat T cells were infected with VSV-G-pseudotyped FIV in the presence or absence of CsA (Fig. 4). As expected, the infectivity of wild type HIV-1 was reduced by the addition of CsA (Fig. 4, top). We obtained reduced infections of FIV in Jurkat cells relative to CRFK cells presumably due to human Trim5α restriction of FIV [23]. However, similar to HIV-1, the infectivity of FIV decreased further by 2–5 fold when CsA was present during infection (Fig. 4, middle). The P90A mutant of FIV which fails to bind cyclophilin A (Fig. 3), in contrast, was not sensitive to CsA treatment (Fig. 4, bottom). These results indicate that FIV, like HIV-1, requires the endogenous cyclophilin A in target cells for optimal infection.


Cyclophilin A interacts with diverse lentiviral capsids.

Lin TY, Emerman M - Retrovirology (2006)

The CypA-dependency of FIV. Jurkat T cells were infected with HIV-1 wild-type (A), FIV wild-type (B), and FIV P90A (C) in the presence or absence of 1.25 μM of CsA. All viruses were first normalized on CRFK cells and equivalent CRFK infectious units were used and are plotted on the X-axis. For example, the amount of virus that gave 20% GFP positive cells on CRFK cells is 0.2 on the X-axis. The infected Jurkat cells were analyzed by flow cytometry and the infectivity is presented as % GFP+ cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1622752&req=5

Figure 4: The CypA-dependency of FIV. Jurkat T cells were infected with HIV-1 wild-type (A), FIV wild-type (B), and FIV P90A (C) in the presence or absence of 1.25 μM of CsA. All viruses were first normalized on CRFK cells and equivalent CRFK infectious units were used and are plotted on the X-axis. For example, the amount of virus that gave 20% GFP positive cells on CRFK cells is 0.2 on the X-axis. The infected Jurkat cells were analyzed by flow cytometry and the infectivity is presented as % GFP+ cells.
Mentions: Previous reports showed that CsA decreases spreading infections of FIV in cells and in animals [24,25]. However, comparisons with HIV-1 were not done. It has been shown that the infectivity of HIV-1 drops 2–5 fold when the CypA/CA interaction is blocked by CsA in Jurkat T cells in single-cycle infection experiments [7-9]. To examine the role of CypA in FIV infection in the same cell type, Jurkat T cells were infected with VSV-G-pseudotyped FIV in the presence or absence of CsA (Fig. 4). As expected, the infectivity of wild type HIV-1 was reduced by the addition of CsA (Fig. 4, top). We obtained reduced infections of FIV in Jurkat cells relative to CRFK cells presumably due to human Trim5α restriction of FIV [23]. However, similar to HIV-1, the infectivity of FIV decreased further by 2–5 fold when CsA was present during infection (Fig. 4, middle). The P90A mutant of FIV which fails to bind cyclophilin A (Fig. 3), in contrast, was not sensitive to CsA treatment (Fig. 4, bottom). These results indicate that FIV, like HIV-1, requires the endogenous cyclophilin A in target cells for optimal infection.

Bottom Line: This binding positively affects some early stage of the viral life-cycle because prevention of binding either by drugs that occupy that active site of cyclophilin A, by mutation in HIV-1 CA, or RNAi that knocks down intracellular CypA level diminishes viral infectivity.We find that diverse lentiviruses, FIV and SIVagmTAN also bind to CypA.Mutagenesis of FIV CA showed that an amino acid that is in a homologous position to the proline at amino acid 90 of HIV-1 CA is essential for FIV interactions with CypA.

View Article: PubMed Central - HTML - PubMed

Affiliation: Pathobiology Graduate Program, University of Washington, Seattle, WA 98195, USA. linty@u.washington.edu

ABSTRACT

Background: The capsid (CA) protein of HIV-1 binds with high affinity to the host protein cyclophilin A (CypA). This binding positively affects some early stage of the viral life-cycle because prevention of binding either by drugs that occupy that active site of cyclophilin A, by mutation in HIV-1 CA, or RNAi that knocks down intracellular CypA level diminishes viral infectivity. The closely related lentivirus, SIVcpz also binds CypA, but it was thought that this interaction was limited to the HIV-1/SIVcpz lineage because other retroviruses failed to interact with CypA in a yeast two-hybrid assay.

Results: We find that diverse lentiviruses, FIV and SIVagmTAN also bind to CypA. Mutagenesis of FIV CA showed that an amino acid that is in a homologous position to the proline at amino acid 90 of HIV-1 CA is essential for FIV interactions with CypA.

Conclusion: These results demonstrate that CypA binding to lentiviruses is more widespread than previously thought and suggest that this interaction is evolutionarily important for lentiviral infection.

Show MeSH
Related in: MedlinePlus