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 Sjöberg, M. Articles by Garoff, H. Search for Related Content PubMed PubMed Citation Articles by Sjöberg, M. Articles by Garoff, H.

 Previous Article  |  Next Article 

Journal of Virology, June 2006, p. 5540-5551, Vol. 80, No. 11
0022-538X/06/$08.00+0     doi:10.1128/JVI.01851-05
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Furin Cleavage Potentiates the Membrane Fusion-Controlling Intersubunit Disulfide Bond Isomerization Activity of Leukemia Virus Env

Department of Biosciences at Novum, Karolinska Institute, S-141 57 Huddinge, Sweden

Received 2 September 2005/ Accepted 12 March 2006

The membrane fusion protein of murine leukemia virus is a trimer of a disulfide-linked peripheral-transmembrane (SU-TM) subunit complex. The intersubunit disulfide bond is in SU linked to a disulfide bond isomerization motif, CXXC, with which the virus controls its fusion reaction (M. Wallin, M. Ekström, and H. Garoff, EMBO J. 23:54-65, 2004). Upon receptor binding the isomerase rearranges the intersubunit disulfide bond into a disulfide bond isomer within the motif. This facilitates SU dissociation and fusion activation in the TM subunit. In the present study we have asked whether furin cleavage of the Env precursor potentiates the isomerase to be triggered. To this end we accumulated the late form of the precursor, gp90, in the cell by incubation in the presence of a furin-inhibiting peptide. The isomerization was done by NP-40 incubation or by a heat pulse under alkylation-free conditions. The cells were lysed in the presence of alkylator, and the precursor was immunoprecipitated, gel isolated, deglycosylated, and subjected to complete trypsin digestion. Disulfide-linked peptide complexes were separated by sodium dodecyl sulfate-tricine-polyacrylamide gel electrophoresis under nonreducing conditions. This assay revealed the size of the characteristic major disulfide-linked peptide complex that differentiates the two isomers of the disulfide bond between Cys336 (or Cys339) and Cys563, i.e., the bond corresponding to the intersubunit disulfide bond. The analyses showed that the isomerase was five- to eightfold more resistant to triggering in the precursor than in the mature, cleaved form. This suggests that the isomerase becomes potentiated for triggering by a structural change in Env that is induced by furin cleavage in the cell.

This article has been cited by other articles:

• Howard, M. W., Travanty, E. A., Jeffers, S. A., Smith, M. K., Wennier, S. T., Thackray, L. B., Holmes, K. V. (2008). Aromatic Amino Acids in the Juxtamembrane Domain of Severe Acute Respiratory Syndrome Coronavirus Spike Glycoprotein Are Important for Receptor-Dependent Virus Entry and Cell-Cell Fusion. J. Virol. 82: 2883-2894 [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]