Two palmitylated cysteine residues of the severe acute respiratory syndrome coronavirus spike (S) protein are critical for S incorporation into virus-like particles, but not for M-S co-localization

J Gen Virol. 2012 Apr;93(Pt 4):823-828. doi: 10.1099/vir.0.038091-0. Epub 2012 Jan 13.

Abstract

The endodomain of several coronavirus (CoV) spike (S) proteins contains palmitylated cysteine residues and enables co-localization and interaction with the CoV membrane (M) protein. Depalmitylation of mouse hepatitis virus S proteins abolished this interaction, resulting in the failure of S incorporation into virions. In contrast, an immunofluorescence assay (IFA) showed that depalmitylated severe acute respiratory syndrome coronavirus (SCoV) S proteins still co-localized with the M protein in the budding site. Here, we determined the ability of depalmitylated SCoV S mutants to incorporate S into virus-like particles (VLPs). IFA confirmed that all SCoV S mutants co-localized with the M protein intracellularly. However, the mutants lacking two cysteine residues (C(1234/1235)) failed to incorporate S into VLPs. This indicated that these palmitylated cysteines are essential for S incorporation, but are not involved in S co-localization mediated by the M protein. Our findings suggest that M-S co-localization and S incorporation occur independently of one another in SCoV virion assembly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Chlorocebus aethiops
  • Coronavirus M Proteins
  • Cysteine / metabolism
  • Membrane Glycoproteins / metabolism*
  • Mice
  • Palmitic Acid / metabolism
  • Severe Acute Respiratory Syndrome / virology*
  • Severe acute respiratory syndrome-related coronavirus / metabolism*
  • Severe acute respiratory syndrome-related coronavirus / physiology
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins / metabolism*
  • Viral Matrix Proteins / metabolism*
  • Virion / metabolism
  • Virion / physiology
  • Virus Assembly / physiology

Substances

  • Coronavirus M Proteins
  • M protein, SARS-CoV
  • Membrane Glycoproteins
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins
  • Viral Matrix Proteins
  • spike glycoprotein, SARS-CoV
  • spike protein, mouse hepatitis virus
  • Palmitic Acid
  • Cysteine