题名：Palmitoylation of the cysteine-rich endodomain of the SARSCcoronavirus spike glycoprotein is important for spike-mediated cell fusion
作者：Chad M. Petit, Vladimir N. Chouljenko, Arun Iyer, Robin Colgrove, Michael Farzan, David M. Knipe and K.G. Kousoulas
来源：Virology[IF=3.08], Volume 360, Issue 2, 10 April 2007, Pages 264-274
摘要： Chad M. Petita, b, Vladimir N. Chouljenkoa, b, Arun Iyera, b, Robin Colgrovec, Michael Farzand, David M. Knipec and K.G. Kousoulasa, b, ,
aDivision of Biotechnology and Molecular Medicine (BIOMMED), USA
bDepartment of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
cDepartment of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA
dPartners AIDS Research Center, Brigham and Women s Hospital, Department of Medicine (Microbiology and Molecular Genetics), Harvard Medical School, Boston, MA 02115, USA
Received 23 June 2006; revised 14 August 2006; accepted 18 October 2006. Available online 28 November 2006.
The SARSCcoronavirus (SARSCCoV) is the etiological agent of the severe acute respiratory syndrome (SARS). The SARSCCoV spike (S) glycoprotein mediates membrane fusion events during virus entry and virus-induced cell-to-cell fusion. The cytoplasmic portion of the S glycoprotein contains four cysteine-rich amino acid clusters. Individual cysteine clusters were altered via cysteine-to-alanine amino acid replacement and the modified S glycoproteins were tested for their transport to cell-surfaces and ability to cause cell fusion in transient transfection assays. Mutagenesis of the cysteine cluster I, located immediately proximal to the predicted transmembrane, domain did not appreciably reduce cell-surface expression, although S-mediated cell fusion was reduced by more than 50% in comparison to the wild-type S. Similarly, mutagenesis of the cysteine cluster II located adjacent to cluster I reduced S-mediated cell fusion by more than 60% compared to the wild-type S, while cell-surface expression was reduced by less than 20%. Mutagenesis of cysteine clusters III and IV did not appreciably affect S cell-surface expression or S-mediated cell fusion. The wild-type S was palmitoylated as evidenced by the efficient incorporation of 3H-palmitic acid in wild-type S molecules. S glycoprotein palmitoylation was significantly reduced for mutant glycoproteins having cluster I and II cysteine changes, but was largely unaffected for cysteine cluster III and IV mutants. These results show that the S cytoplasmic domain is palmitoylated and that palmitoylation of the membrane proximal cysteine clusters I and II may be important for S-mediated cell fusion. 6.