Lytic viruses infecting a chlorella-like alga

Etten, James L. Van; Burbank, Dwight E.; Schuster, Anne; Meints, Russel H.

doi:10.1016/0042-6822(85)90452-0

Cited by 71 publications

(61 citation statements)

References 11 publications

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“…Twenty-nine of the 42 viruses used in this study were isolated from water samples collected in different regions of the United States in 1983-1984(Van Etten et al 1985aSchuster et al 1986) and seven were isolated from water collected in China in 1987 (Zhang et al 1988). Including PBCV-1, which was isolated in 1981, several criteria were used to group these 37 viruses into 16 classes (Table 1) (Van Etten et al 1991).…”

Section: The Pdg Gene Is Widespread In the Chlorella Virusesmentioning

confidence: 99%

Intron Conservation in a UV-Specific DNA Repair Gene Encoded by Chlorella Viruses

Sun

Liu²,

McCullough

et al. 2000

J Mol Evol

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Abstract. Large dsDNA-containing chlorella viruses encode a pyrimidine dimer-specific glycosylase (PDG) that initiates repair of UV-induced pyrimidine dimers. The PDG enzyme is a homologue of the bacteriophage T4-encoded endonuclease V. The pdg gene was cloned and sequenced from 42 chlorella viruses isolated over a 12-year period from diverse geographic regions. Surprisingly, the pdg gene from 15 of these 42 viruses contain a 98-nucleotide intron that is 100% conserved among the viruses and another 4 viruses contain an 81-nucleotide intron, in the same position, that is nearly 100% identical (one virus differed by one base). In contrast, the nucleotides in the pdg coding regions (exons) from the introncontaining viruses are 84 to 100% identical. The introns in the pdg gene have 5Ј-AG/GTATGT and 3Ј-TTGCAG/ AA splice site sequences which are characteristic of nuclear-located, spliceosomal processed pre-mRNA introns. The 100% identity of the 98-nucleotide intron sequence in the 15 viruses and the near-perfect identity of an 81-nucleotide intron sequence in another 4 viruses imply strong selective pressure to maintain the DNA sequence of the intron when it is in the pdg gene. However, the ability of intron-plus and intron-minus viruses to repair UV-damaged DNA in the dark was nearly identical. These findings contradict the widely accepted dogma that intron sequences are more variable than exon sequences.

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Section: The Pdg Gene Is Widespread In the Chlorella Virusesmentioning

confidence: 99%

Intron Conservation in a UV-Specific DNA Repair Gene Encoded by Chlorella Viruses

Sun

Liu²,

McCullough

et al. 2000

J Mol Evol

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“…In addition, 24 of the 37 viral DNAs contain m6A in amounts varying from 1.5% to 37% of the total adenine (142,212). At one end of the spectrum is a virus with 0.12% m5C and no m6A and at the other end, a virus with 45% m5C and 37% m6A.…”

Section: Dna Methyltransferases and Site-specific Endonucleasesmentioning

confidence: 99%

“…For example, 1.9% of the cytosines are m5C and 1.5% of the adenines are m6A (212). In fact, the genomes of all the chlorella viruses have methylated bases and the viruses can be distinguished from one another by the site-specificity and amount of DNA methylation (142,143,208).…”

Section: Pbcv-1 Genomementioning

confidence: 99%

“…The PBCV-1 host, Chlorella NC64A, has a G+C content of 67%. The genome of Chlorella NC64A also contains methylated nucleotides; 21% of the cytosines are 5-methylcytosine (m5C) and 0.6% of the adenines are N6-methyladenine (m6A) (212). (b) The cell wall polysaccharides of Chlorella species vary widely (108,194,235), even among isolates assigned to the same species (235).…”

Section: (A) Viruses That Infect Chlorella Isolate Nc64a (Nc64a Virmentioning

confidence: 99%

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Unusual Life Style of Giant Chlorella Viruses

Etten

2003

Annu. Rev. Genet.

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175

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Paramecium bursaria chlorella virus (PBCV-1) is the prototype of a family of large, icosahedral, plaque-forming, dsDNA viruses that replicate in certain unicellular, eukaryotic chlorella-like green algae. Its 330-kb genome contains ~373 protein-encoding genes and 11 tRNA genes. The predicted gene products of ~50% of these genes resemble proteins of known function, including many that are unexpected for a virus, e.g., ornithine decarboxylase, hyaluronan synthase, GDP-D-mannose 4,6 dehydratase, and a potassium ion channel protein. In addition to their large genome size, the chlorella viruses have other features that distinguish them from most viruses. These features include: (a) The viruses encode multiple DNA methyltransferases and DNA site-specific endonucleases. (b) The viruses encode at least some, if not all, of the enzymes required to glycosylate their proteins. (c) PBCV-1 has at least three types of introns, a self-splicing intron in a transcription factorlike gene, a spliceosomal processed intron in its DNA polymerase gene, and a small intron in one of its tRNA genes. (d) Many chlorella virus-encoded proteins are either the smallest or among the smallest proteins of their class. (e) Accumulating evidence indicates that the chlorella viruses have a very long evolutionary history.

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“…The isolation and characterization of some viruses has also been described from several types of hosts (Dodds & Cole 1980, Stanker et al 1981, Van Etten et al 1981, 1985, Martin & Benson 1982, Schuster et al 1986a. This paper describes the presence of VLP infecting cultures of the apicomplexan protozoan Perkinsus atlanticus (Levine 1978), a new recently described species (Azevedo 1989).…”

Section: Introductionmentioning

confidence: 99%

Virus-like particles in Perkinsus atlanticus (Apicomplexa, Perkinsidae)

Azevedo¹

1990

Dis. Aquat. Org.

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Virus-like particles (VLP) were observed in different phases of the in vitro zoosporulation of Perkinsus atlanticus (Apicomplexa, Perlunsidae) which parasitized the gill tissues of Rudtapes decussatus (Molluscs, Bivalvia). These VLP were represented by numerous electron-dense bodies (ca 125 nm diameter) not previously described in similar culture processes. The VLP were densely packed in a membrane-lined inclusion of isolated host-cell cytoplasm of parasitic origin. They were also found among prezoosporangia and zoosporangia of P. atlanticus, a species that causes recurrent mortalities in the clam R. decussatus. The ultrastructural organization of these VLP seems to represent a new and unclassified virus of P. atlanticus.

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Lytic viruses infecting a chlorella-like alga

Cited by 71 publications

References 11 publications

Intron Conservation in a UV-Specific DNA Repair Gene Encoded by Chlorella Viruses

Intron Conservation in a UV-Specific DNA Repair Gene Encoded by Chlorella Viruses

Unusual Life Style of Giant Chlorella Viruses

Virus-like particles in Perkinsus atlanticus (Apicomplexa, Perkinsidae)

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