JCB logo
R&D Systems: New Poster Available
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article
Right arrow Full Text
Right arrow Full Text (PDF, 407K)
Right arrow PPT slides of all figures
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hernandez, L. D.
Right arrow Articles by White, J. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hernandez, L. D.
Right arrow Articles by White, J. M.
Right arrowPubmed/NCBI databases
*Compound via MeSH
*Substance via MeSH
Hazardous Substances DB
*GLUTAMIC ACID HYDROCHLORIDE
Social Bookmarking
 Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Facebook   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

© The Rockefeller University Press, 0021-9525/1997//1455 $5.00
The Journal of Cell Biology, Volume 139, Number 6, , 1997 1455-1464


Article

Activation of a Retroviral Membrane Fusion Protein: Soluble Receptor-induced Liposome Binding of the ALSV Envelope Glycoprotein



Lorraine D. Hernandez*,{ddagger}, Reuben J. Peters{ddagger},§, Sue E. Delos*, John A.T. Young||, David A. Agard{ddagger},§, and Judith M. White*

* Department of Cell Biology, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908; {ddagger} Department of Biochemistry and Biophysics, § Howard Hughes Medical Institute, University of California, San Francisco, California 94143; and || Department of Microbiology and Molecular Genetics, Harvard Medical School, Cambridge, Massachusetts 02138

It is not known how membrane fusion proteins that function at neutral pH, for example the human immunodeficiency virus envelope (Env) glycoprotein and intracellular fusion machines, are activated for target bilayer binding. We have addressed this question using a soluble oligomeric form of an avian retroviral Env glycoprotein (API) and soluble forms of its receptor. Binding of soluble receptor to API induces API to bind to liposomes composed of phosphatidylcholine and cholesterol at neutral pH. Liposome binding only occurs at fusion permissive temperatures (T > 20°C), is complete between 2 to 5 min at 37°C, and is stable to high salt, carbonate, and urea. Liposome binding is mediated by the ectodomain of the transmembrane subunit of API, and a mutant with a Val to Glu substitution in the Env fusion peptide (located in the ectodomain of the transmembrane subunit) shows significantly reduced liposome binding. Moreover, under conditions of equivalent binding to API, a mutant receptor that does not support infection (Zingler, K., and J.A.T. Young. 1996. J. Virol. 70:7510–7516) does not induce significant liposome binding. Our results indicate that a highly specific interaction between an avian retroviral Env and its receptor activates the retroviral glycoprotein for target bilayer binding at neutral pH in much the same way as low pH activates the influenza hemagglutinin. Our findings are discussed in terms of the mechanisms of viral and cellular fusion proteins that function at neutral pH.


Abbreviations used in this paper: ALSV, avian leukosis and sarcoma virus; API, GPI-linked ALSV subgroup A Env glycoprotein; BHA, bromelain-released hemagglutinin; DAF, decay-accelerating factor; DTT, dithiothreitol; ECL, enhanced chemiluminescence; Env, envelope glycoprotein; GPI, glycosylphosphatidylinositol; HA, hemagglutinin; HIV, human immunodeficiency virus; LDL, low density lipoprotein; NSF, N-ethylmaleimide-sensitive factor; PI-PLC, phosphatidylinositol-specific phospholipase-C; RT, room temperature; SFV, Semliki Forest virus; sTva, soluble ALSV subgroup A receptor; SU, surface; TM, transmembrane; Tva, ALSV subgroup A receptor; wt, wild-type.

Work in Dr. White's laboratory was supported by a grant from the National Institutes of Health (A122470). L.D. Hernandez was supported in part by a predoctoral fellowship from the Howard Hughes Medical Institute. D.A. Agard is an Investigator of the Howard Hughes Medical Institute.

Address all correspondence to Judith M. White, Department of Cell Biology, University of Virginia, Health Sciences Center, Box 439, Charlottesville, VA 22908. Tel.: (804) 924-2593. Fax: (804) 982-3912. e-mail: jw7g{at}virginia.edu



Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Facebook Facebook   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents