Ribosome-inactivating activity and cDNA cloning of antiviral protein isoforms of Chenopodium album.
We have characterized a novel type I ribosome-inactivating protein (CAP30) from the leaves of Chenopodium album. Purified native CAP30 depurinated the ribosomes of Chenopodium, tomato, and tobacco leaves in vitro. To further characterize this protein, cDNA clones were isolated from a leaf cDNA library using a DNA probe derived from the N-terminal amino acid sequence. Two full-length cDNA clones, CAP30A and CAP30B, were isolated. The two clones were highly homologous (91.4% identity over 280 amino acids) at the deduced amino acid level. Both contain a putative signal peptide of 25 amino acid and a conserved domain commonly found in ribosome-inactivating proteins. This suggests that CAP30 is a single-chain ribosome-inactivating protein. Expression of CAP30 mRNA peaked twice, at 12 and 72 h, after tobacco mosaic virus (TMV) infection or wounding. Transformed Escherichia coli cells expressing pre- or mature CAP had greatly reduced growth rates. These results suggest that CAP30 functions as a broad-spectrum defense-related protein with both antiviral and anti-microbial activity.
Park
Jong-Sug
JS
Metabolic Engineering Division, National Institute of Agricultural Biotechnology, Rural Development Administrate, Suwon 441-707, Korea. jongsug@rda.go.kr
Hwang
Duk-Ju
DJ
Lee
Si-Myung
SM
Kim
Yeong-Tae
YT
Choi
Sang-Bong
SB
Cho
Kang-Jin
KJ
D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000494:pharmacology; D027463:Chenopodium album / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D015723:Gene Library; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000737:chemistry* / Q000235:genetics*; D010802:Phylogeny; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry; D020033:Protein Isoforms; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry; D054788:Ribosome Inactivating Proteins; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D000998:Antiviral Agents; D018076:DNA, Complementary; D010940:Plant Proteins; D020033:Protein Isoforms; D021382:Protein Sorting Signals; D012313:RNA; D009699:N-Glycosyl Hydrolases; D054788:Ribosome Inactivating Proteins