Cooperative involvement of the S1 and S2 subunits of the murine coronavirus spike protein in receptor binding and extended host range.
To study the process of spike (S)-receptor interaction during coronavirus entry, we evaluated the contributions of mutations in different regions of the murine hepatitis virus (MHV) S protein to natural receptor murine carcinoembryonic antigen-related cell adhesion molecule 1a (CEACAM1a) dependence and to the acquisition of extended host range. Extended-host-range variants of MHV strain A59 were previously obtained from persistently infected cells (J. H. Schickli, B. D. Zelus, D. E. Wentworth, S. G. Sawicki, and K. V. Holmes, J. Virol. 71:9499-9504, 1997). These variant viruses contain several mutations in the S protein that confer to the viruses the ability to enter cells in a heparan sulfate-dependent manner (C. A. de Haan, Z. Li, E. te Lintelo, B. J. Bosch, B. J. Haijema, and P. J. M. Rottier, J. Virol. 79:14451-14456, 2005). While the parental MHV-A59 is fully dependent on murine CEACAM1a for its entry, viruses carrying the variant mutations in the amino-terminal part of their S protein had become dependent on both CEACAM1a and heparan sulfate. Substitutions in a restricted, downstream part of the S protein encompassing heptad repeat region 1 (HR1) and putative fusion peptide (FP) did not alter the CEACAM1a dependence. However, when the mutations in both parts of the S protein were combined, the resulting viruses became independent of CEACAM1a and acquired the extended host range. In addition, these viruses showed a decreased binding to and inhibition by soluble CEACAM1a. The observations suggest that the amino-terminal region of the S protein, including the receptor-binding domain, and a region in the central part of the S protein containing HR1 and FP, i.e., regions far apart in the linear sequence, communicate and may even interact physically in the higher-order structure of the spike.
de Haan
Cornelis A M
CA
Virology Division, Department of Infectious Diseases and Immunology, Yalelaan 1, 3584 CL Utrecht, The Netherlands. c.a.m.dehaan@vet.uu.nl
Te Lintelo
Eddie
E
Li
Zhen
Z
Raaben
Matthijs
M
Wurdinger
Tom
T
Bosch
Berend Jan
BJ
Rottier
Peter J M
PJ
D019943:Amino Acid Substitution; D000818:Animals; D002272:Carcinoembryonic Antigen / Q000378:metabolism*; D002415:Cats; D002460:Cell Line; D017930:Genes, Reporter; D006497:Heparan Sulfate; D006801:Humans; D008156:Luciferases / Q000032:analysis / Q000235:genetics; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D006517:Murine hepatitis virus / Q000235:genetics / Q000502:physiology*; D020125:Mutation, Missense; D011485:Protein Binding; D011991:Receptors, Virus / Q000378:metabolism*; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D053585:Virus Attachment
D002272:Carcinoembryonic Antigen; D006497:Heparan Sulfate; D008156:Luciferases; D008562:Membrane Glycoproteins; D011991:Receptors, Virus; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C486183:Ceacam1 protein, mouse; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus