EcxAB is a founding member of a new family of metalloprotease AB5 toxins with a hybrid cholera-like B subunit

Natasha May-Yoke Ng, Dene Littler, Adrienne Webster Paton, Jerome Le Nours, Jamie Rossjohn, James C Paton, Travis Clarke Beddoe

Research output: Contribution to journalArticleResearchpeer-review

20 Citations (Scopus)


AB5 toxins are composed of an enzymatic A subunit that disrupts cellular function associated with a pentameric B subunit required for host cell invasion. EcxAB is an AB5 toxin isolated from clinical strains of Escherichia coli classified as part of the cholera family due to B subunit homology. Cholera-group toxins have catalytic ADP-ribosyltransferases as their A subunits, so it was surprising that EcxA did not. We confirmed that EcxAB self-associates as a functional toxin and obtained its structure. EcxAB is a prototypical member of a hybrid AB5 toxin family containing metzincin-type metalloproteases as their active A subunit paired to a cholera-like B subunit. Furthermore, EcxA is distinct from previously characterized proteases and thus founds an AB5-associated metzincin family that we term the toxilysins. EcxAB provides the first observation of conserved B subunit usage across different AB5 toxin families and provides evidence that the intersubunit interface of these toxins is far more permissive than previously supposed.
Original languageEnglish
Pages (from-to)2003 - 2013
Number of pages11
Issue number11
Publication statusPublished - 2013

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