title: Importance of SARS-CoV spike protein Trp-rich region in viral infectivity.
abstract: SARS-CoV entry is mediated by spike glycoprotein. During the viral and host cellular membrane fusion, HR1 and HR2 form 6-helix bundle, positioning the fusion peptide closely to the C-terminal region of ectodomain to drive apposition and subsequent membrane fusion. Connecting to the HR2 region is a Trp-rich region which is absolutely conserved in members of coronaviruses. To investigate the importance of Trp-rich region in SARS-CoV entry, we produced different mutated S proteins using Alanine scan strategy. SARS-CoV pseudotyped with mutated S protein was used to measure viral infectivity. To restore the aromaticity of Ala-mutants, we performed rescue experiments using phenylalanine substitutions. Our results show that individually substituted Ala-mutants substantially decrease infectivity by >90%, global Ala-mutants totally abrogated infectivity. In contrast, Phe-substituted mutants are able to restore 10-25% infectivity comparing to the wild-type. The results suggest that the Trp-rich region of S protein is essential for SARS-CoV infectivity.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
authors.forename: Yanning
authors.initials: Y
authors.lastname: Lu
authors.forename: Tuan Ling
authors.initials: TL
authors.lastname: Neo
authors.forename: Ding Xiang
authors.initials: DX
authors.lastname: Liu
authors.forename: James P
authors.initials: JP
authors.lastname: Tam
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D045473:Severe acute respiratory syndrome-related coronavirus / Q000235:genetics / Q000502:physiology*; D064370:Spike Glycoprotein, Coronavirus; D014364:Tryptophan / Q000737:chemistry* / Q000235:genetics; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics; D053586:Virus Internalization
chemical_list: D008562:Membrane Glycoproteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus; D014364:Tryptophan