title: A variable region on the chlorovirus CVK2 genome contains five copies of the gene for Vp260, a viral-surface glycoprotein.
abstract: A 22.2-kb variable region near the left end of the chlorovirus CVK2 genome that was previously supposed to be expanded compared to the PBCV-1 genome was characterized. This region contains a tandem array of five gene copies for the Vp260-like protein, a viral-surface glycoprotein. The authentic 104-kDa Vp260 was found to be encoded at another site on the genome and to contain 13 internal tandem repeats of 61-65 amino acids, similar to the prominent Rickettsia surface antigen. The extra copies were also found to retain 10 of the internal repeats, despite the C-terminal deletions or extensions. These extra copies are conserved among chloroviruses isolated in various areas of Japan. By Northern blot analysis, these genes were demonstrated to be expressed late in infection. The proteins are incorporated into virions, as revealed by comparing viral structural proteins between wild-type and deletion mutants. These results indicate that extra copies of Vp260-like proteins encoded in a variable region on the genome may give variations in the surface nature of the chloroviral particles.
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: Niti
authors.initials: N
authors.lastname: Chuchird
authors.forename: Kensho
authors.initials: K
authors.lastname: Nishida
authors.forename: Takeru
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Fujie
authors.forename: Shoji
authors.initials: S
authors.lastname: Usami
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamada
mesh_terms: D000595:Amino Acid Sequence; D002708:Chlorella / Q000821:virology; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D018628:Gene Dosage; D014644:Genetic Variation; D016679:Genome, Viral; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017862:Phycodnaviridae / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D020080:Tandem Repeat Sequences / Q000235:genetics; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D014759:Viral Envelope Proteins; C459403:Vp260 protein, chlorovirus