Shiga toxin
From Proteopedia
(Difference between revisions)
| Line 5: | Line 5: | ||
==Structure== | ==Structure== | ||
| - | Shiga Toxin consists consists of an [http://en.wikipedia.org/wiki/AB5_toxin AB5] hexamer | + | Shiga Toxin consists consists of an [http://en.wikipedia.org/wiki/AB5_toxin AB5] hexamer.<ref name=Fraser>PMID: 7656009</ref> The 5 subunit B pentamer interacts with a single A subunit via a C-terminal helix and 4 stranded beta-sheet.<ref name=Fraser> 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> |
| + | |||
| + | ==Function== | ||
| + | Shiga Toxin acts as an N-glycosidase, removing an adenine from the 60S ribosomal rRNA of a target cell leading to reduced protein synthesis.<ref name=Di>PMID: 21184769</ref> The B subunit is necessary for binding to eukaryotic cell surface, where it is then endocytosed and proteolytically cleaved into two active A subunits and a B subunit. On the A subunit Tyr77, Tyr114, Glu167, Arg170, and Trp203 are all essential in glycosidic activity.<ref name=Di> | ||
==References== | ==References== | ||
{{Reflist}} | {{Reflist}} | ||
Revision as of 02:44, 14 October 2011
|
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.[1]
Structure
Shiga Toxin consists consists of an AB5 hexamer.[2] The 5 subunit B pentamer interacts with a single A subunit via a C-terminal helix and 4 stranded beta-sheet.[2] The B subunit is necessary for binding to eukaryotic cell surface, where it is then endocytosed and proteolytically cleaved into two active A subunits and a B subunit. On the A subunit Tyr77, Tyr114, Glu167, Arg170, and Trp203 are all essential in glycosidic activity.[3]
