This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Netter, R. C. Articles by Bates, P. Search for Related Content PubMed PubMed Citation Articles by Netter, R. C. Articles by Bates, P.

 Previous Article  |  Next Article 

Journal of Virology, December 2004, p. 13430-13439, Vol. 78, No. 24
0022-538X/04/$08.00+0     DOI: 10.1128/JVI.78.24.13430-13439.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Heptad Repeat 2-Based Peptides Inhibit Avian Sarcoma and Leukosis Virus Subgroup A Infection and Identify a Fusion Intermediate

Robert C. Netter,¹ Sean M. Amberg,¹ John W. Balliet,^1, Mark J. Biscone,¹ Arwen Vermeulen,¹ Laurie J. Earp,² Judith M. White,² and Paul Bates^1*

Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania,¹ Department of Microbiology, University of Virginia, Charlottesville, Virginia²

Received 12 May 2004/ Accepted 26 July 2004

Fusion proteins of enveloped viruses categorized as class I are typified by two distinct heptad repeat domains within the transmembrane subunit. These repeats are important structural elements that assemble into the six-helix bundles characteristic of the fusion-activated envelope trimer. Peptides derived from these domains can be potent and specific inhibitors of membrane fusion and virus infection. To facilitate our understanding of retroviral entry, peptides corresponding to the two heptad repeat domains of the avian sarcoma and leukosis virus subgroup A (ASLV-A) TM subunit of the envelope protein were characterized. Two peptides corresponding to the C-terminal heptad repeat (HR2), offset from one another by three residues, were effective inhibitors of infection, while two overlapping peptides derived from the N-terminal heptad repeat (HR1) were not. Analysis of envelope mutants containing substitutions within the HR1 domain revealed that a single amino acid change, L62A, significantly reduced sensitivity to peptide inhibition. Virus bound to cells at 4°C became sensitive to peptide within the first 5 min of elevating the temperature to 37°C and lost sensitivity to peptide after 15 to 30 min, consistent with a transient intermediate in which the peptide binding site is exposed. In cell-cell fusion experiments, peptide inhibitor sensitivity occurred prior to a fusion-enhancing low-pH pulse. Soluble receptor for ASLV-A induces a lipophilic character in the envelope which can be measured by stable liposome binding, and this activation was found to be unaffected by inhibitory HR2 peptide. Finally, receptor-triggered conformational changes in the TM subunit were also found to be unaffected by inhibitory peptide. These changes are marked by a dramatic shift in mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, from a subunit of 37 kDa to a complex of about 80 kDa. Biotinylated HR2 peptide bound specifically to the 80-kDa complex, demonstrating a surprisingly stable envelope conformation in which the HR2 binding site is exposed. These experiments support a model in which receptor interaction promotes formation of an envelope conformation in which the TM subunit is stably associated with its target membrane and is able to bind a C-terminal peptide.

Present address: Department of Medicine, Harvard Medical School at the Beth Israel Deaconess Medical Center, Boston, MA 02215.

This article has been cited by other articles:

• Delos, S. E., Brecher, M. B., Chen, Z., Melder, D. C., Federspiel, M. J., White, J. M. (2008). Cysteines Flanking the Internal Fusion Peptide Are Required for the Avian Sarcoma/Leukosis Virus Glycoprotein To Mediate the Lipid Mixing Stage of Fusion with High Efficiency. J. Virol. 82: 3131-3134 [Abstract] [Full Text]  
• Sjoberg, M., Lindqvist, B., Garoff, H. (2008). Stabilization of TM Trimer Interactions during Activation of Moloney Murine Leukemia Virus Env. J. Virol. 82: 2358-2366 [Abstract] [Full Text]  
• Long, G., Pan, X., Vlak, J. M. (2008). Conserved Leucines in N-Terminal Heptad Repeat HR1 of Envelope Fusion Protein F of Group II Nucleopolyhedroviruses Are Important for Correct Processing and Essential for Fusogenicity. J. Virol. 82: 2437-2447 [Abstract] [Full Text]  
• Ujike, M., Nishikawa, H., Otaka, A., Yamamoto, N., Yamamoto, N., Matsuoka, M., Kodama, E., Fujii, N., Taguchi, F. (2008). Heptad Repeat-Derived Peptides Block Protease-Mediated Direct Entry from the Cell Surface of Severe Acute Respiratory Syndrome Coronavirus but Not Entry via the Endosomal Pathway. J. Virol. 82: 588-592 [Abstract] [Full Text]  
• Porotto, M., Doctor, L., Carta, P., Fornabaio, M., Greengard, O., Kellogg, G. E., Moscona, A. (2006). Inhibition of Hendra Virus Fusion. J. Virol. 80: 9837-9849 [Abstract] [Full Text]  
• Wallin, M., Ekstrom, M., Garoff, H. (2006). Receptor-Triggered but Alkylation-Arrested Env of Murine Leukemia Virus Reveals the Transmembrane Subunit in a Prehairpin Conformation. J. Virol. 80: 9921-9925 [Abstract] [Full Text]  
• Chai, N., Bates, P. (2006). Na+/H+ exchanger type 1 is a receptor for pathogenic subgroup J avian leukosis virus. Proc. Natl. Acad. Sci. USA 103: 5531-5536 [Abstract] [Full Text]  
• Amberg, S. M., Netter, R. C., Simmons, G., Bates, P. (2006). Expanded Tropism and Altered Activation of a Retroviral Glycoprotein Resistant to an Entry Inhibitor Peptide. J. Virol. 80: 353-359 [Abstract] [Full Text]  
• Wallin, M., Loving, R., Ekstrom, M., Li, K., Garoff, H. (2005). Kinetic Analyses of the Surface-Transmembrane Disulfide Bond Isomerization-Controlled Fusion Activation Pathway in Moloney Murine Leukemia Virus. J. Virol. 79: 13856-13864 [Abstract] [Full Text]  
• Simmons, G., Gosalia, D. N., Rennekamp, A. J., Reeves, J. D., Diamond, S. L., Bates, P. (2005). Inhibitors of cathepsin L prevent severe acute respiratory syndrome coronavirus entry. Proc. Natl. Acad. Sci. USA 102: 11876-11881 [Abstract] [Full Text]  
• Melikyan, G. B., Barnard, R. J. O., Abrahamyan, L. G., Mothes, W., Young, J. A. T. (2005). Imaging individual retroviral fusion events: From hemifusion to pore formation and growth. Proc. Natl. Acad. Sci. USA 102: 8728-8733 [Abstract] [Full Text]  
• Delos, S. E., Godby, J. A., White, J. M. (2005). Receptor-Induced Conformational Changes in the SU Subunit of the Avian Sarcoma/Leukosis Virus A Envelope Protein: Implications for Fusion Activation. J. Virol. 79: 3488-3499 [Abstract] [Full Text]