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Viroporin potential of the lentivirus lytic peptide (LLP) domains of the HIV-1 gp41 protein.

Costin JM, Rausch JM, Garry RF, Wimley WC - Virol. J. (2007)

Bottom Line: Mechanisms by which HIV-1 mediates reductions in CD4+ cell levels in infected persons are being intensely investigated, and have broad implications for AIDS drug and vaccine development.These results suggest that the C-terminal domains of HIV-1 Env proteins may form an ion channel, or viroporin.Increased understanding of the function of LLP domains and their role in the viral replication cycle could allow for the development of novel HIV drugs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biotechnology Research Group, Department of Biology, Florida Gulf Coast University, 10501 FGCU Blvd. S., Fort Myers, FL 33965, USA. jcostin@fgcu.edu

ABSTRACT

Background: Mechanisms by which HIV-1 mediates reductions in CD4+ cell levels in infected persons are being intensely investigated, and have broad implications for AIDS drug and vaccine development. Virally induced changes in membrane ionic permeability induced by lytic viruses of many families contribute to cytopathogenesis. HIV-1 induces disturbances in plasma membrane ion transport. The carboxyl terminus of TM (gp41) contains potential amphipathic alpha-helical motifs identified through their structural similarities to naturally occurring cytolytic peptides. These sequences have been dubbed lentiviral lytic peptides (LLP) -1, -2, and -3.

Results: Peptides corresponding to the LLP domains (from a clade B virus) partition into lipid membranes, fold into alpha-helices and disrupt model membrane permeability. A peptide corresponding to the LLP-1 domain of a clade D HIV-1 virus, LLP-1D displayed similar activity to the LLP-1 domain of the clade B virus in all assays, despite a lack of amino acid sequence identity.

Conclusion: These results suggest that the C-terminal domains of HIV-1 Env proteins may form an ion channel, or viroporin. Increased understanding of the function of LLP domains and their role in the viral replication cycle could allow for the development of novel HIV drugs.

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Related in: MedlinePlus

LLP peptides form α-helices in the presence of lipid. Circular dichroism spectroscopy of LLP peptides in PO4 buffer (open squares) and in the presence of 90%POPC:10%POPG (filled squares). Spectroscopic analysis revealed that each peptide possessed the characteristic minima at 208 nm and 222 nm indicating α-helical character. (a) LLP-1 labeled with NBD; (b) LLP-2 labeled with NBD; (c) LLP-3; (d) LLP-1D labeled with NBD. (e) The percent α-helicity was calculated from the CD spectroscopy curves in figure a-d for each peptide using the following formula: Θ222/(1–2.5/n)(40,000), where n = the number of residues present in the peptide.
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Figure 2: LLP peptides form α-helices in the presence of lipid. Circular dichroism spectroscopy of LLP peptides in PO4 buffer (open squares) and in the presence of 90%POPC:10%POPG (filled squares). Spectroscopic analysis revealed that each peptide possessed the characteristic minima at 208 nm and 222 nm indicating α-helical character. (a) LLP-1 labeled with NBD; (b) LLP-2 labeled with NBD; (c) LLP-3; (d) LLP-1D labeled with NBD. (e) The percent α-helicity was calculated from the CD spectroscopy curves in figure a-d for each peptide using the following formula: Θ222/(1–2.5/n)(40,000), where n = the number of residues present in the peptide.

Mentions: Peptides were synthesized from the primary amino acid sequences given in Figure 1C. Fluorescent NBD (4-chloro-7-nitrobenz-2-oxa-1, 3-diazol) labels were attached to the N terminus of peptides lacking tryptophan residues (LLP-1, LLP-2, and LLP-1D) for lipid membrane partitioning and circular dichroism experiments, as well as for quantification purposes. Experimental evidence exists suggesting that peptides corresponding to these domains adopt α-helical secondary structure in the context of some lipid environments [11-14]. Figure 2 shows the circular dichroism spectra of peptides corresponding to each of the three LLP domains in the presence (unfilled squares) and absence (filled squares) of lipid vesicles composed of 10% POPG: 90% POPC. LLP-1 peptide in the presence of KPO4 buffer alone gave the characteristic spectrum of a randomly ordered peptide. After the addition of 10% POPG: 90% POPC LUVs, a shift towards a more ordered structure was observed, with minima at 208 nm and 222 nm (vertical dashed lines) corresponding to characteristic α-helical spectra. Similar results were observed with peptides corresponding to the LLP-2 (Fig. 2B), LLP-3 (Fig. 2C), and LLP-1D (Fig. 2D) domains, where dramatically enhanced α-helical secondary structure was observed in the presence of a membranes. The percent α-helicity was calculated from the Θ222 value observed in the above spectra and the results are presented in figure 2E.


Viroporin potential of the lentivirus lytic peptide (LLP) domains of the HIV-1 gp41 protein.

Costin JM, Rausch JM, Garry RF, Wimley WC - Virol. J. (2007)

LLP peptides form α-helices in the presence of lipid. Circular dichroism spectroscopy of LLP peptides in PO4 buffer (open squares) and in the presence of 90%POPC:10%POPG (filled squares). Spectroscopic analysis revealed that each peptide possessed the characteristic minima at 208 nm and 222 nm indicating α-helical character. (a) LLP-1 labeled with NBD; (b) LLP-2 labeled with NBD; (c) LLP-3; (d) LLP-1D labeled with NBD. (e) The percent α-helicity was calculated from the CD spectroscopy curves in figure a-d for each peptide using the following formula: Θ222/(1–2.5/n)(40,000), where n = the number of residues present in the peptide.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211469&req=5

Figure 2: LLP peptides form α-helices in the presence of lipid. Circular dichroism spectroscopy of LLP peptides in PO4 buffer (open squares) and in the presence of 90%POPC:10%POPG (filled squares). Spectroscopic analysis revealed that each peptide possessed the characteristic minima at 208 nm and 222 nm indicating α-helical character. (a) LLP-1 labeled with NBD; (b) LLP-2 labeled with NBD; (c) LLP-3; (d) LLP-1D labeled with NBD. (e) The percent α-helicity was calculated from the CD spectroscopy curves in figure a-d for each peptide using the following formula: Θ222/(1–2.5/n)(40,000), where n = the number of residues present in the peptide.
Mentions: Peptides were synthesized from the primary amino acid sequences given in Figure 1C. Fluorescent NBD (4-chloro-7-nitrobenz-2-oxa-1, 3-diazol) labels were attached to the N terminus of peptides lacking tryptophan residues (LLP-1, LLP-2, and LLP-1D) for lipid membrane partitioning and circular dichroism experiments, as well as for quantification purposes. Experimental evidence exists suggesting that peptides corresponding to these domains adopt α-helical secondary structure in the context of some lipid environments [11-14]. Figure 2 shows the circular dichroism spectra of peptides corresponding to each of the three LLP domains in the presence (unfilled squares) and absence (filled squares) of lipid vesicles composed of 10% POPG: 90% POPC. LLP-1 peptide in the presence of KPO4 buffer alone gave the characteristic spectrum of a randomly ordered peptide. After the addition of 10% POPG: 90% POPC LUVs, a shift towards a more ordered structure was observed, with minima at 208 nm and 222 nm (vertical dashed lines) corresponding to characteristic α-helical spectra. Similar results were observed with peptides corresponding to the LLP-2 (Fig. 2B), LLP-3 (Fig. 2C), and LLP-1D (Fig. 2D) domains, where dramatically enhanced α-helical secondary structure was observed in the presence of a membranes. The percent α-helicity was calculated from the Θ222 value observed in the above spectra and the results are presented in figure 2E.

Bottom Line: Mechanisms by which HIV-1 mediates reductions in CD4+ cell levels in infected persons are being intensely investigated, and have broad implications for AIDS drug and vaccine development.These results suggest that the C-terminal domains of HIV-1 Env proteins may form an ion channel, or viroporin.Increased understanding of the function of LLP domains and their role in the viral replication cycle could allow for the development of novel HIV drugs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biotechnology Research Group, Department of Biology, Florida Gulf Coast University, 10501 FGCU Blvd. S., Fort Myers, FL 33965, USA. jcostin@fgcu.edu

ABSTRACT

Background: Mechanisms by which HIV-1 mediates reductions in CD4+ cell levels in infected persons are being intensely investigated, and have broad implications for AIDS drug and vaccine development. Virally induced changes in membrane ionic permeability induced by lytic viruses of many families contribute to cytopathogenesis. HIV-1 induces disturbances in plasma membrane ion transport. The carboxyl terminus of TM (gp41) contains potential amphipathic alpha-helical motifs identified through their structural similarities to naturally occurring cytolytic peptides. These sequences have been dubbed lentiviral lytic peptides (LLP) -1, -2, and -3.

Results: Peptides corresponding to the LLP domains (from a clade B virus) partition into lipid membranes, fold into alpha-helices and disrupt model membrane permeability. A peptide corresponding to the LLP-1 domain of a clade D HIV-1 virus, LLP-1D displayed similar activity to the LLP-1 domain of the clade B virus in all assays, despite a lack of amino acid sequence identity.

Conclusion: These results suggest that the C-terminal domains of HIV-1 Env proteins may form an ion channel, or viroporin. Increased understanding of the function of LLP domains and their role in the viral replication cycle could allow for the development of novel HIV drugs.

Show MeSH
Related in: MedlinePlus