Shiga toxin: Difference between revisions
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==Introduction== | ==Introduction== | ||
'''Shiga Toxins''' are a family of AB5 toxins which cause dysentery in humans. They are primarily secreted by Shiga toxin-encoding Escherichia coli (STEC), notably by the 0157:H7 strain.<ref name=Wagner>PMID: 12010491</ref> The stx gene is not endogenous to these strains, but is introduced by environmental prophages of the lambda bacteriophage family and incorporated into the E. Coli genome.<ref name=Wagner>PMID: 12010491</ref> | '''Shiga Toxins''' are a family of [http://en.wikipedia.org/wiki/AB5_toxin AB5] toxins which cause dysentery in humans. They are primarily secreted by Shiga toxin-encoding Escherichia coli (STEC), notably by the 0157:H7 strain.<ref name=Wagner>PMID: 12010491</ref> The stx gene is not endogenous to these strains, but is introduced by environmental prophages of the lambda bacteriophage family and incorporated into the E. Coli genome.<ref name=Wagner>PMID: 12010491</ref> | ||
==Structure== | ==Structure== | ||
Shiga Toxin consists consists of an | Shiga Toxin consists consists of an AB5 hexamer.<ref name=Fraser>PMID: 7656009</ref> The <scene name='Shiga_toxin/B_subunits/1'>5 subunit B pentamer</scene> interacts with the <scene name='Shiga_toxin/A_subunits/1'>two separate A subunits</scene> via a | ||
<scene name='Shiga_toxin/A-b_interaction/1'>C-terminal helix of hydrophobic subunits packed antiparallel to 5 B helixes</scene> and | <scene name='Shiga_toxin/A-b_interaction/1'>C-terminal helix of hydrophobic subunits packed antiparallel to 5 B helixes</scene> and | ||
<scene name='Shiga_toxin_1/Beta_sheet/1'>4 antiparallel beta sheets</scene>.<ref name=Fraser>PMID: 7656009</ref>. The glycosidase active site is located on the A subunit, but is blocked by the B subunit until they are cleaved and an active A subunit is released into the target cell.<ref name=Fraser>PMID: 7656009</ref> | <scene name='Shiga_toxin_1/Beta_sheet/1'>4 antiparallel beta sheets</scene>.<ref name=Fraser>PMID: 7656009</ref>. The glycosidase active site is located on the A subunit, but is blocked by the B subunit until they are cleaved and an active A subunit is released into the target cell.<ref name=Fraser>PMID: 7656009</ref> | ||