Unexpected activity of saporins

Barbieri, Luigi; Gorini, P; Valbonesi, Paola; Castiglioni, Paola; Stirpe, Fiorenzo

doi:10.1038/372624a0

Cited by 111 publications

(91 citation statements)

References 9 publications

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“…Leaf extracts from both plants not only inhibit protein synthesis, but also release adenine from DNA. It seems reasonable to assume that the effect on DNA of semi-purified extracts is due to the RIP contained in the leaves, consistently with the release of adenine from DNA by saporins [8], PAP and H. crepitans RIP (present results) and other RIPs (Barbieri et al, unpublished results). In the leaves from the same plants both the translation inhibitory and the DNA deadenylating activities increase during senescence or under stressing conditions.…”

Section: Discussionmentioning

confidence: 71%

“…The RIPs purified from H. crepitans and P. americana release adenine from DNA as saporins do [8]. Leaf extracts from both plants not only inhibit protein synthesis, but also release adenine from DNA.…”

Section: Discussionmentioning

confidence: 99%

“…More recently it was observed that some RIPs released more than one adenine per ribosome [6], saporin-L1, a RIP from the leaves of Saponaria offieinalis [7], being particularly active. Subsequently it was found that (i) this RIP released many, probably all, adenine residues not only from rRNA, but from all other tested RNAs, from poly(A) and from herring sperm DNA [8], and (ii) that other RIPs of either type tested released adenine from the same DNA (unpublished results). Thus some RIPs can be considered polynucleotide:adenosine nucleosidases.…”

Section: Introductionmentioning

confidence: 99%

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Activities associated with the presence of ribosome‐inactivating proteins increase in senescent and stressed leaves

et al. 1996

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The ribosome-inactivating proteins (RIPs) from Hura crepitans and Phytolaeca americana release adenine from herring sperm DNA. Leaf extracts from these plants show the same enzymatic activities as the RIPs. The translation inhibitory activity and the activity on DNA are both increased in the leaves of both plants during senescence or when subjected to heat or osmotic stress. It is proposed that a physiological role of RIPs could be to intervene in the death of plant cells.

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Section: Discussionmentioning

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Activities associated with the presence of ribosome‐inactivating proteins increase in senescent and stressed leaves

et al. 1996

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“…For instance, it has been shown that several RIPs can release adenine from multiple sites in rRNA (5). Furthermore, saporin-L1 can release adenine residues from a variety of nucleic acid substrates, including poly(A), mRNA, tRNA, and DNA (6,7). More than 50 other RIPs are active on DNA (8).…”

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confidence: 99%

The N-Glycosidase Activity of the Ribosome-inactivating Protein ME1 Targets Single-stranded Regions of Nucleic Acids Independent of Sequence or Structural Motifs

Park¹,

Vepachedu²,

Owens

et al. 2004

Journal of Biological Chemistry

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ME 1 , a type I ribosome-inactivating protein (RIP), belongs to a family of enzymes long believed to possess rRNA N-glycosidase activity directed solely at the universally conserved residue A4324 in the sarcin/ricin loop of large eukaryotic and prokaryotic rRNAs. We have investigated the effect of modifying the structure of nonribosomal RNA substrates on their interaction with ME 1 and other RIPs. ME 1 was shown to depurinate a variety of partially denatured nucleic acids, randomly removing adenine residues from single-stranded regions and, to a lesser extent, guanine residues from wobble basepairs in hairpin stems. A defined sequence motif was not required for recognition of non-paired adenosines and cleavage of the N-glycosidic bond. Substrate recognition and ME 1 activity appeared to depend on the physical availability of nucleotides, and denaturation of nucleic acid substrates increased their interaction with ME 1 . Pretreatment of mRNA at 75°C rather than 60°C, for example, lowered the apparent K D from 87.1 to 73.9 nM, making it more vulnerable to depurination by RIPs. Exposure to ME 1 in vitro completely abolished the infectivity of partially denatured RNA transcripts of the potato spindle tuber viroid, suggesting that RIPs may target invading nucleic acids before they reach host ribosomes in vivo. Our data suggest that the extensive folding of many potential substrates interferes with their ability to interact with RIPs, thereby blocking their inactivation by ME 1

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“…Very recently, it has been reported that saporin L1, an RIP from Saponaria officinalis L., displays depurinating activity on viral RNA and herring sperm DNA [13], which could account for the antiviral activity generally assigned to RIPs [14]. However, despite the antiviral role assigned to RIPs, the precise physiological role played by RIPs in plants is as yet unknown and requires much more research.…”

Section: Introductionmentioning

confidence: 99%

Ebulitins: A new family of type 1 ribosome‐inactivating proteins (rRNA N‐glycosidases) from leaves of Sambucus ebulus L. that coexist with the type 2 ribosome‐inactivating protein ebulin 1

et al. 1995

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A new family of single chain (type 1) ribosome-inactivating proteins (RIPs), that we have named ebulitins, have been found in mature leaves of Sambucus ebulus L., a caprifoliaceae plant also known to contain a non-toxic two chain (type 2) RIP named ebulin 1 in its leaves. Ebulitins are basic proteins of Mr 32,000, 29,000 and 29,000 for ebulitins a,/3 and T, respectively. The simultaneous presence of different basic type 1 and acidic type 2 RIPs in the same plant and in the same tissue is described here for the first time and opens a new door in research into RIPs.

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Unexpected activity of saporins

Cited by 111 publications

References 9 publications

Activities associated with the presence of ribosome‐inactivating proteins increase in senescent and stressed leaves

Activities associated with the presence of ribosome‐inactivating proteins increase in senescent and stressed leaves

The N-Glycosidase Activity of the Ribosome-inactivating Protein ME1 Targets Single-stranded Regions of Nucleic Acids Independent of Sequence or Structural Motifs

Ebulitins: A new family of type 1 ribosome‐inactivating proteins (rRNA N‐glycosidases) from leaves of Sambucus ebulus L. that coexist with the type 2 ribosome‐inactivating protein ebulin 1

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