Toxins 2011, 3(7), 834-847; doi:10.3390/toxins3070834

Adapting Yeast as Model to Study Ricin Toxin A Uptake and Trafficking

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Received: 7 June 2011; in revised form: 7 June 2011 / Accepted: 28 June 2011 / Published: 5 July 2011
(This article belongs to the Special Issue Ricin Toxin)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: The plant A/B toxin ricin represents a heterodimeric glycoprotein belonging to the family of ribosome inactivating proteins, RIPs. Its toxicity towards eukaryotic cells results from the depurination of 28S rRNA due to the N-glycosidic activity of ricin toxin A chain, RTA. Since the extention of RTA by a mammalian-specific endoplasmic reticulum (ER) retention signal (KDEL) significantly increases RTA in vivo toxicity against mammalian cells, we here analyzed the phenotypic effect of RTA carrying the yeast-specific ER retention motif HDEL. Interestingly, such a toxin (RTAHDEL) showed a similar cytotoxic effect on yeast as a corresponding RTAKDEL variant on HeLa cells. Furthermore, we established a powerful yeast bioassay for RTA in vivo uptake and trafficking which is based on the measurement of dissolved oxygen in toxin-treated spheroplast cultures of S. cerevisiae. We show that yeast spheroplasts are highly sensitive against external applied RTA and further demonstrate that its toxicity is greatly enhanced by replacing the C-terminal KDEL motif by HDEL. Based on the RTA resistant phenotype seen in yeast knock-out mutants defective in early steps of endocytosis (∆end3) and/or in RTA depurination activity on 28S rRNA (∆rpl12B) we feel that the yeast-based bioassay described in this study is a powerful tool to dissect intracellular A/B toxin transport from the plasma membrane through the endosomal compartment to the ER.
Keywords: ricin toxin A chain; ER retention signal; yeast spheroplasts; toxin endocytosis and transport; oyxgen-sensor microtiter plate; H/KDEL
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MDPI and ACS Style

Becker, B.; Schmitt, M.J. Adapting Yeast as Model to Study Ricin Toxin A Uptake and Trafficking. Toxins 2011, 3, 834-847.

AMA Style

Becker B, Schmitt MJ. Adapting Yeast as Model to Study Ricin Toxin A Uptake and Trafficking. Toxins. 2011; 3(7):834-847.

Chicago/Turabian Style

Becker, Björn; Schmitt, Manfred J. 2011. "Adapting Yeast as Model to Study Ricin Toxin A Uptake and Trafficking." Toxins 3, no. 7: 834-847.

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