Chlorella Virus PBCV-1 Encodes a Functional Homospermidine Synthase

Sequence analysis of the 330-kb genome of chlorella virus Paramecium bursaria chlorella virus 1 (PBCV-1) revealed an open reading frame, A237R, that encodes a protein with 34% amino acid identity to homospermidine synthase from Rhodopseudomonas viridis. Expression of the a237r gene product in Escher...

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Bibliographic Details
Published in:Virology (New York, N.Y.) N.Y.), 1999-10, Vol.263 (1), p.254-262
Main Authors: Kaiser, Annette, Vollmert, Michael, Tholl, Dorothea, Graves, Michael V., Gurnon, James R., Xing, Weimei, Lisec, Amber D., Nickerson, Kenneth W., Van Etten, James L.
Format: Article
Language:English
Subjects:
Alkyl and Aryl Transferases - chemistry
Alkyl and Aryl Transferases - genetics
Alkyl and Aryl Transferases - metabolism
Amino Acid Sequence
Chlorella - virology
Chlorella virus
chlorella viruses
DNA - analysis
DNA, Viral - analysis
DNA, Viral - genetics
dsDNA virus
genbank/u42580
Genes, Viral
homospermidine
homospermidine synthase
Molecular Sequence Data
ornithine decarboxylase
Ornithine Decarboxylase - metabolism
Paramecium bursaria Chlorella virus 1
PBCV-1
Phycodnaviridae
Phycodnaviridae - enzymology
Phycodnaviridae - genetics
Plant Diseases - virology
polyamines
Polyamines - metabolism
Recombinant Proteins - metabolism
Spermidine - biosynthesis
Virion
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Summary:Sequence analysis of the 330-kb genome of chlorella virus Paramecium bursaria chlorella virus 1 (PBCV-1) revealed an open reading frame, A237R, that encodes a protein with 34% amino acid identity to homospermidine synthase from Rhodopseudomonas viridis. Expression of the a237r gene product in Escherichia coli established that the recombinant enzyme catalyzes the NAD+-dependent formation of homospermidine from two molecules of putrescine. The a237r gene is expressed late in PBCV-1 infection. Both uninfected and PBCV-1-infected chlorella, as well as PBCV-1 virions, contain homospermidine, along with the more common polyamines putrescine, spermidine, and cadaverine. The total number of polyamine molecules per virion (∼539) is too small to significantly neutralize the virus double-stranded DNA (>660,000 nucleotides). Consequently, the biological significance of the homospermidine synthase gene is unknown. However, the gene is widespread among the chlorella viruses. To our knowledge, this is the first report of a virus encoding an enzyme involved in polyamine biosynthesis.
ISSN:0042-6822
1096-0341
DOI:10.1006/viro.1999.9972