Studies on membrane topology, N-glycosylation and functionality of SARS-CoV membrane protein

• Published in: Virology Journal 2009, Vol.6 (79), p.79
• Main Authors: Voß, Daniel, Pfefferle, Susanne, Drosten, Christian, Stevermann, Lea, Traggiai, Elisabetta, Lanzavecchia, Antonio, Becker, Stephan
• Format: Report
• Language: English
• Subjects: Glycosylation; Health aspects; Membrane proteins; Physiological aspects; Risk factors; Severe acute respiratory syndrome; Viruses
• ISSN: 1743-422X; 1743-422X
• DOI: 10.1186/1743-422X-6-79

The glycosylated membrane protein M of the severe acute respiratory syndrome associated coronavirus (SARS-CoV) is the main structural component of the virion and mediates assembly and budding of viral particles. The membrane topology of SARS-CoV M and the functional significance of its N-glycosylation are not completely understood as is its interaction with the surface glycoprotein S. Using biochemical and immunofluorescence analyses we found that M consists of a short glycosylated N-terminal ectodomain, three transmembrane segments and a long, immunogenic C-terminal endodomain. Although the N-glycosylation site of M seems to be highly conserved between group 1 and 3 coronaviruses, studies using a recombinant SARS-CoV expressing a glycosylation-deficient M revealed that N-glycosylation of M neither influence the shape of the virions nor their infectivity in cell culture. Further functional analysis of truncated M proteins showed that the N-terminal 134 amino acids comprising the three transmembrane domains are sufficient to mediate accumulation of M in the Golgi complex and to enforce recruitment of the viral spike protein S to the sites of virus assembly and budding in the ERGIC.