title: Identification of the Fusion Peptide-Containing Region in Betacoronavirus Spike Glycoproteins.
abstract: The fusion peptides (FP) play an essential role in fusion of viral envelope with cellular membranes. The location and properties of the FPs in the spike (S) glycoproteins of different coronaviruses (CoV) have not yet been determined. Through amino acid sequence analysis of S proteins of representative CoVs, we identified a common region as a possible FP (pFP) that shares the characteristics of FPs of class I viral fusion proteins, including high Ala/Gly content, intermediate hydrophobicity, and few charged residues. To test the hypothesis that this region contains the CoV FP, we systemically mutated every residue in the pFP of Middle East respiratory syndrome betacoronavirus (MERS-CoV) and found that 11 of the 22 residues in the pFP (from G953 to L964, except for A956) were essential for S protein-mediated cell-cell fusion and virus entry. The synthetic MERS-CoV pFP core peptide (955IAGVGWTAGL964) induced extensive fusion of liposome membranes, while mutant peptide failed to induce any lipid mixing. We also selectively mutated residues in pFPs of two other β-CoVs, severe acute respiratory syndrome coronavirus (SARS-CoV) and mouse hepatitis virus (MHV). Although the amino acid sequences of these two pFPs differed significantly from that of MERS-CoV and each other, most of the pFP mutants of SARS-CoV and MHV also failed to mediate membrane fusion, suggesting that these pFPs are also the functional FPs. Thus, the FPs of 3 different lineages of β-CoVs are conserved in location within the S glycoproteins and in their functions, although their amino acid sequences have diverged significantly during CoV evolution.
  
  
  
  Within the class I viral fusion proteins of many enveloped viruses, the FP is the critical mediator of fusion of the viral envelope with host cell membranes leading to virus infection. FPs from within a virus family, like influenza viruses or human immunodeficiency viruses (HIV), tend to share high amino acid sequence identity. In this study, we determined the location and amino acid sequences of the FPs of S glycoproteins of 3 β-CoVs, MERS-CoV, SARS-CoV, and MHV, and demonstrated that they were essential for mediating cell-cell fusion and virus entry. Interestingly, in marked contrast to the FPs of influenza and HIV, the primary amino acid sequences of the FPs of β-CoVs in 3 different lineages differed significantly. Thus, during evolution the FPs of β-CoVs have diverged significantly in their primary sequences while maintaining the same essential biological functions. Our findings identify a potential new target for development of drugs against CoVs.
authors.affiliation: MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Xiuyuan
authors.initials: X
authors.lastname: Ou
authors.affiliation: MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Wangliang
authors.initials: W
authors.lastname: Zheng
authors.affiliation: MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Yiwei
authors.initials: Y
authors.lastname: Shan
authors.affiliation: MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Zhixia
authors.initials: Z
authors.lastname: Mu
authors.affiliation: Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Dominguez
authors.affiliation: Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA.
authors.forename: Kathryn V
authors.initials: KV
authors.lastname: Holmes
authors.affiliation: MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China zqian2013@sina.com.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Qian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019143:Evolution, Molecular; D057809:HEK293 Cells; D006801:Humans; D008561:Membrane Fusion; D051379:Mice; D065207:Middle East Respiratory Syndrome Coronavirus / Q000737:chemistry* / Q000235:genetics; D006517:Murine hepatitis virus / Q000737:chemistry* / Q000235:genetics; D009154:Mutation; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics; D045473:Severe acute respiratory syndrome-related coronavirus / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment; D064370:Spike Glycoprotein, Coronavirus / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D053586:Virus Internalization
chemical_list: D010455:Peptides; D064370:Spike Glycoprotein, Coronavirus