Shiga toxin: Difference between revisions
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Shiga Toxin acts as an N-glycosidase, removing an adenine from the 28S ribosomal rRNA of a target cell which leads to inhibition of protein elongation and ultimately cellular apoptosis.<ref name=Di>PMID: 21184769</ref> The B subunit is necessary for binding to globo series glycolipid globotriaosylceramide (Gb<sub>3</sub>), a eukaryotic membrane receptor, where it is then endocytosed and proteolytically cleaved into an active A subunit and a B subunit.<ref name=Lenz>PMID: 2170899</ref> The B subunit is not active in the depurination of of 28S rRNA, but is essential for GB<sub>3</sub> binding and therefore essential for toxicity. Once in the cytosol the A subunit is free to interact with and inactivate 28S rRNA. On the A subunit <scene name='Shiga_toxin_1/Active_site_zoomed_in/1'>Tyr77, Tyr114, Glu167, Arg170, and Trp203</scene> are all essential in glycosidic activity.<ref name=Di>PMID: 21184769</ref> This mechanism (B subunit binding to globotriaosylceramide and A subunit depurinating 28S rRNA) is conserved amongst the Stx family as well as the ricin toxin. | Shiga Toxin acts as an N-glycosidase, removing an adenine from the 28S ribosomal rRNA of a target cell which leads to inhibition of protein elongation and ultimately cellular apoptosis.<ref name=Di>PMID: 21184769</ref> The B subunit is necessary for binding to globo series glycolipid globotriaosylceramide (Gb<sub>3</sub>), a eukaryotic membrane receptor, where it is then endocytosed and proteolytically cleaved into an active A subunit and a B subunit.<ref name=Lenz>PMID: 2170899</ref> The B subunit is not active in the depurination of of 28S rRNA, but is essential for GB<sub>3</sub> binding and therefore essential for toxicity. Once in the cytosol the A subunit is free to interact with and inactivate 28S rRNA. On the A subunit <scene name='Shiga_toxin_1/Active_site_zoomed_in/1'>Tyr77, Tyr114, Glu167, Arg170, and Trp203</scene> are all essential in glycosidic activity.<ref name=Di>PMID: 21184769</ref> This mechanism (B subunit binding to globotriaosylceramide and A subunit depurinating 28S rRNA) is conserved amongst the Stx family as well as the ricin toxin. | ||
==3D structures of shiga toxin== | ==3D structures of shiga toxin== | ||
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</StructureSection> | |||
==References== | ==References== | ||
{{Reflist}} | {{Reflist}} | ||
[[Category:Topic Page]] | [[Category:Topic Page]] | ||