title: Spike protein assembly into the coronavirion: exploring the limits of its sequence requirements.
abstract: The coronavirus spike (S) protein, required for receptor binding and membrane fusion, is incorporated into the assembling virion by interactions with the viral membrane (M) protein. Earlier we showed that the ectodomain of the S protein is not involved in this process. Here we further defined the requirements of the S protein for virion incorporation. We show that the cytoplasmic domain, not the transmembrane domain, determines the association with the M protein and suffices to effect the incorporation into viral particles of chimeric spikes as well as of foreign viral glycoproteins. The essential sequence was mapped to the membrane-proximal region of the cytoplasmic domain, which is also known to be of critical importance for the fusion function of the S protein. Consistently, only short C-terminal truncations of the S protein were tolerated when introduced into the virus by targeted recombination. The important role of the about 38-residues cytoplasmic domain in the assembly of and membrane fusion by this approximately 1300 amino acids long protein is discussed.
authors.affiliation: Virology Division, Department of Infectious Diseases and Immunology, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
authors.forename: Berend Jan
authors.initials: BJ
authors.lastname: Bosch
authors.forename: Cornelis A M
authors.initials: CA
authors.lastname: de Haan
authors.forename: Saskia L
authors.initials: SL
authors.lastname: Smits
authors.forename: Peter J M
authors.initials: PJ
authors.lastname: Rottier
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002415:Cats; D002460:Cell Line; D000086862:Coronavirus M Proteins; D016765:Coronavirus, Feline / Q000235:genetics / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral; D006801:Humans; D008561:Membrane Fusion; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D006517:Murine hepatitis virus / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism; D014771:Virion / Q000378:metabolism*; D019065:Virus Assembly
chemical_list: D000086862:Coronavirus M Proteins; D008562:Membrane Glycoproteins; D012367:RNA, Viral; D011993:Recombinant Fusion Proteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D014763:Viral Matrix Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus