Studies on membrane topology, N-glycosylation and functionality of SARS-CoV membrane protein.
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.
Voss
Daniel
D
Institute of Virology, Philipps-University Marburg, Marburg, Germany. vossd@rki.de
Pfefferle
Susanne
S
Drosten
Christian
C
Stevermann
Lea
L
Traggiai
Elisabetta
E
Lanzavecchia
Antonio
A
Becker
Stephan
S
D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D000086862:Coronavirus M Proteins; D006031:Glycosylation; D006056:Golgi Apparatus / Q000821:virology; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D045473:Severe acute respiratory syndrome-related coronavirus / Q000737:chemistry* / Q000502:physiology*; D017384:Sequence Deletion; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000378:metabolism; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D053586:Virus Internalization; D014779:Virus Replication
D000086862:Coronavirus M Proteins; C000706237:M protein, SARS-CoV; D008562:Membrane Glycoproteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D014763:Viral Matrix Proteins