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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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Related in: MedlinePlus

Infectivity of HIV-1 WT, G89V mutant and FIV under the TrimCyp restriction. CRFK and CRFK-TrimCyp cells were infected with HIV-1 wild-type (A), HIV-1 G89V (B), and FIV (C) in the presence or absence of CsA. The infected cells were analyzed by flow cytometry and the infectivity is presented as percentage of cells that were GFP+ (on a log scale).
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Figure 1: Infectivity of HIV-1 WT, G89V mutant and FIV under the TrimCyp restriction. CRFK and CRFK-TrimCyp cells were infected with HIV-1 wild-type (A), HIV-1 G89V (B), and FIV (C) in the presence or absence of CsA. The infected cells were analyzed by flow cytometry and the infectivity is presented as percentage of cells that were GFP+ (on a log scale).

Mentions: The TrimCyp protein from owl monkeys strongly restricts HIV-1 because the C-terminal CypA portion of the protein binds to HIV-1 CA, while the N-terminal portion of the protein leads to premature uncoating or degradation of incoming virions [13,14,17,18]. We therefore asked whether FIV is also sensitive to TrimCyp restriction as an indirect measure of CA-CypA recognition. Cells expressing TrimCyp were generated and infected with VSV-G pseudotyped wild-type HIV-1, a HIV-1 G89V mutant (CA with a G89V mutation does not bind CypA [2]), and FIV (Fig. 1). Infections were done in the presence or absence of CsA to verify the dependence of the restriction on CypA function. Because infections were done with viruses that encode GFP (see Methods), the number of infected cells could be directly analyzed by flow cytometry (Fig. 1). Consistent with previous reports [17,18], HIV-1 is sensitive to TrimCyp restriction and the restriction can be neutralized by treatment of cells with CsA (Fig. 1A), while the negative control, the HIV-1 G89V mutant, is not restricted by TrimCyp (Fig. 1B). We found that FIV behaves similar to HIV-1 in that it was restricted by TrimCyp, and this restriction is reversed by CsA (Fig. 1C).


Cyclophilin A interacts with diverse lentiviral capsids.

Lin TY, Emerman M - Retrovirology (2006)

Infectivity of HIV-1 WT, G89V mutant and FIV under the TrimCyp restriction. CRFK and CRFK-TrimCyp cells were infected with HIV-1 wild-type (A), HIV-1 G89V (B), and FIV (C) in the presence or absence of CsA. The infected cells were analyzed by flow cytometry and the infectivity is presented as percentage of cells that were GFP+ (on a log scale).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Infectivity of HIV-1 WT, G89V mutant and FIV under the TrimCyp restriction. CRFK and CRFK-TrimCyp cells were infected with HIV-1 wild-type (A), HIV-1 G89V (B), and FIV (C) in the presence or absence of CsA. The infected cells were analyzed by flow cytometry and the infectivity is presented as percentage of cells that were GFP+ (on a log scale).
Mentions: The TrimCyp protein from owl monkeys strongly restricts HIV-1 because the C-terminal CypA portion of the protein binds to HIV-1 CA, while the N-terminal portion of the protein leads to premature uncoating or degradation of incoming virions [13,14,17,18]. We therefore asked whether FIV is also sensitive to TrimCyp restriction as an indirect measure of CA-CypA recognition. Cells expressing TrimCyp were generated and infected with VSV-G pseudotyped wild-type HIV-1, a HIV-1 G89V mutant (CA with a G89V mutation does not bind CypA [2]), and FIV (Fig. 1). Infections were done in the presence or absence of CsA to verify the dependence of the restriction on CypA function. Because infections were done with viruses that encode GFP (see Methods), the number of infected cells could be directly analyzed by flow cytometry (Fig. 1). Consistent with previous reports [17,18], HIV-1 is sensitive to TrimCyp restriction and the restriction can be neutralized by treatment of cells with CsA (Fig. 1A), while the negative control, the HIV-1 G89V mutant, is not restricted by TrimCyp (Fig. 1B). We found that FIV behaves similar to HIV-1 in that it was restricted by TrimCyp, and this restriction is reversed by CsA (Fig. 1C).

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