SARS-CoV envelope protein palmitoylation or nucleocapid association is not required for promoting virus-like particle production

Background: coronavirus membrane (m) proteins are capable of interacting with nucleocapsid (n) and envelope (e) proteins. severe acute respiratory syndrome coronavirus (sars-cov) m co-expression with either n or e is sufficient for producing virus-like particles (vlps),although at a lower level compared to m,n and e co-expression. whether e can release from cells or e/n interaction exists so as to contribute to enhanced vlp production is unknown. it also remains to be determined whether e palmitoylation or disulfide bond formation plays a role in sars-cov virus assembly. results: sars-cov n is released from cells through an association with e protein-containing vesicles. further analysis suggests that domains involved in e/n interaction are largely located in both carboxyl-terminal regions. changing all three e cysteine residues to alanines did not exert negative effects on e release,e association with n,or e enhancement of vlp production,suggesting that e palmitoylation modification or disulfide bond formation is not required for sars-cov virus assembly. we found that removal of the last e carboxyl-terminal residue markedly affected e release,n association,and vlp incorporation,but did not significantly compromise the contribution of e to efficient vlp production. conclusions: the independence of the sars-cov e enhancement effect on vlp production from its viral packaging capacity suggests a distinct sars-cov e role in virus assembly. © 2014 tseng et al.; licensee biomed central ltd.