title: C-terminal repetitive motifs in Vp130 present at the unique vertex of the Chlorovirus capsid are essential for binding to the host Chlorella cell wall.
abstract: Previously, Vp130, a chloroviral structural protein, was found to have host-cell-wall-binding activity for NC64A-viruses (PBCV-1 and CVK2). In this study, we have isolated and characterized the corresponding protein from chlorovirus CVGW1, one of Pbi-viruses that have a different host range. In NC64A-viruses, Vp130 consists of a highly conserved N-terminal domain, internal repeats of 70-73 aa motifs and a C-terminal domain occupied by 23-26 tandem repeats of a PAPK motif. However, CVGW1 was found to have a slightly different Vp130 construction where the PAPK repeats were not in the C-terminus but internal. Immunofluorescence microscopy with a specific antibody revealed that the C-terminal region containing the Vp130 repetitive motifs from PBCV-1 and CVK2 was responsible for binding to Chlorella cell walls. Furthermore, by immunoelectron microscopy and immunofluorescence microscopy, Vp130 was localized at a unique vertex of the chlorovirus particle and was found to be masked through binding to the host cells. These results suggested that Vp130 is localized at a unique vertex on the virion, with the C-terminal repetitive units outside for cell wall binding.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Onimatsu
authors.forename: Kei
authors.initials: K
authors.lastname: Suganuma
authors.forename: Shushi
authors.initials: S
authors.lastname: Uenoyama
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamada
mesh_terms: D000595:Amino Acid Sequence; D002473:Cell Wall / Q000821:virology; D002708:Chlorella / Q000821:virology*; D005814:Genes, Viral; D007494:Ireland; D008969:Molecular Sequence Data; D017862:Phycodnaviridae / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D016415:Sequence Alignment; D013045:Species Specificity; D013329:Structure-Activity Relationship; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000502:physiology; D014771:Virion / Q000737:chemistry; D014779:Virus Replication
chemical_list: D014759:Viral Envelope Proteins