The mechanism of action of ricin and related toxic lectins on eukaryotic ribosomes. The site and the characteristics of the modification in 28 S ribosomal RNA caused by the toxins

Ricin is a potent cytotoxic protein derived from the higher plant Ricinus communis that inactivates eukaryotic ribosomes. In this paper we have studied the mechanism of action of ricin A-chain on rat liver ribosomes in vitro. Our findings indicate that the toxin inactivates the ribosomes by modifyin...

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Bibliographic Details
Published in:The Journal of biological chemistry 1987-04, Vol.262 (12), p.5908-5912
Main Authors: Endo, Y., Mitsui, K., Motizuki, M., Tsurugi, K.
Format: Article
Language:English
Subjects:
Animals
Base Sequence
Biological and medical sciences
Cell structures and functions
Fundamental and applied biological sciences. Psychology
Lectins - toxicity
Liver - drug effects
Liver - metabolism
Liver - pathology
Molecular and cellular biology
Molecular Weight
Rats
Ribosome
Ribosomes - drug effects
Ribosomes - metabolism
Ricin - toxicity
Ricinus communis
RNA, Ribosomal - drug effects
RNA, Ribosomal - metabolism
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Summary:Ricin is a potent cytotoxic protein derived from the higher plant Ricinus communis that inactivates eukaryotic ribosomes. In this paper we have studied the mechanism of action of ricin A-chain on rat liver ribosomes in vitro. Our findings indicate that the toxin inactivates the ribosomes by modifying both or either of two nucleoside residues, G4323 and A4324, in 28 S rRNA. These nucleotides are located close to the alpha-sarcin cleavage site and become resistant to all ribonucleases tested. The examination of the lability of phosphodiester bonds of these nucleotides to both mild alkaline digestion and aniline treatment at acidic pH suggests that the base of A4324 is removed by the toxin. This unique activity of ricin A-chain was also observed when naked 28 S rRNA is used as a substrate, indicating that the toxin directly acts on the RNA. Similar activity on 28 S rRNA is also exhibited by abrin and modeccin, ricin-related toxins, suggesting a general mechanistic pathway for ribosome inactivation by lectin toxins.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)45660-8