Isolation and characterization of four type 2 ribosome inactivating pulchellin isoforms from Abrus pulchellus seeds

Abstract

Abrus pulchellus seeds contain at least seven closely related and highly toxic type 2 ribosome‐inactivating pulchellins, each consisting of a toxic A‐chain linked to a sugar binding B‐chain. In the present study, four pulchellin isoforms (termed P I, P II, P III and P IV) were isolated by affinity, ion exchange and chromatofocusing chromatographies, and investigated with respect to toxicity and sugar binding specificity. Half maximal inhibitory concentration and median lethal dose values indicate that P I and P II have similar toxicities and that both are more toxic to cultured HeLa cells and mice than P III and P IV. Interestingly, the secondary structural characteristics and sugar binding properties of the respective pairs of isoforms correlate well with the two toxicity levels, in that P I/P II and P III/P IV form two specific subgroups. From the deduced amino acids sequences of the four isoforms, it is clear that the highest similarity within each subgroup is found to occur within domain 2 of the B‐chains, suggesting that the disparity in toxicity levels might be attributed to subtle differences in B‐chain‐mediated cell surface interactions that precede and determine toxin uptake pathways.

Toxicological studies on plant proteins: a review

“…The mechanism (ribosome-inactivating effects) of the toxicity of pulchellin is similar to that of ricin and abrin introduced above with some variations (also see Araújo et al, 2010;Castilho et al, 2008;Silva et al, 2005). Stirpe et al (2007) isolated, purified and identified stenodactylin and lanceolin [which are highly toxic to cells (in which they induce apoptosis) and to mice] from the caudices of Passifloraceae Adenia lanceolata and A. stenodactyla, respectively.…”

“…The mechanism (ribosome‐inactivating effects) of the toxicity of pulchellin is similar to that of ricin and abrin introduced above with some variations (also see Araújo et al ., ; Castilho et al ., ; Silva et al ., ).…”

Detection of Abrin-Like and Prepropulchellin-Like Toxin Genes and Transcripts Using Whole Genome Sequencing and Full-Length Transcript Sequencing of Abrus precatorius

“…Previous reports suggest that up to four distinct abrin and pulchellin protein isoforms exist. Both of these proteins have been shown to be toxic to human/primate cell lines and during mouse assays at varying levels, depending on the abrin [7] and pulchellin [8] isoforms isolated. Furthermore, agglutinin, an evolutionary variant of pulchellin and abrin, has been shown to be less toxic due to the lack of a critical hydrogen bond that causes a lower binding in between Abrin and 28S RNA [9].…”

“…In the mid-2000s, the Araújo Lab at the University of Sao Paulo cloned and expressed the A-and B-chains of pulchellin (orthologs of abrin genes) to test the toxicity of the compounds produced by the related species Abrus pulchellus. This group subsequently sequenced four mRNA prepropulchellin types [8,14,15]. Additional sequencing of standard plant genetic barcode regions for species identification and phylogenetic analysis are in abundance in GenBank as well, but complete genome sequencing and assembly of an Abrus genome has not been completed to date.…”

Production and Characterization of Pulchellin A chain conjugated to HIV mAbs, and study its selective cytotoxicity against cells expressing HIV envelope

“…Recently, studies of endocytosis and intracellular transport of Pulchellin have been done in the Institute of Physics in Sao Carlos, University of Sao Paulo. (26)(27)(28) It is assumed that the mechanism of Pulchellin for entering target cells would be similar to ricin.…”