Structural Basis for the Activation of Cholera Toxin by Human ARF6-GTP

  title={Structural Basis for the Activation of Cholera Toxin by Human ARF6-GTP},
  author={Claire J O'Neal and Michael G Jobling and Randall K. Holmes and Wim G. J. Hol},
  pages={1093 - 1096}
The Vibrio cholerae bacterium causes devastating diarrhea when it infects the human intestine. The key event is adenosine diphosphate (ADP)–ribosylation of the human signaling protein GSα, catalyzed by the cholera toxin A1 subunit (CTA1). This reaction is allosterically activated by human ADP-ribosylation factors (ARFs), a family of essential and ubiquitous G proteins. Crystal structures of a CTA1:ARF6-GTP (guanosine triphosphate) complex reveal that binding of the human activator elicits… 
A Mutational Analysis of Residues in Cholera Toxin A1 Necessary for Interaction with Its Substrate, the Stimulatory G Protein Gsα
Variants with single alanine substitutions at surface-exposed residues within these CTA1 motifs were tested for assembly into holotoxin and ADP-ribosylating activity against Gsα and diethylamino-(benzylidineamino)-guanidine (DEABAG), a small substrate predicted to fit into the CTA2 active site.
The Cholera Toxin A13 Subdomain Is Essential for Interaction with ADP-Ribosylation Factor 6 and Full Toxic Activity but Is Not Required for Translocation from the Endoplasmic Reticulum to the Cytosol
It is found that the A13 subdomain of CTA1 is important both for interaction with ARF6 and for full expression of enzyme activity in vivo and Surprisingly, however, the A 13 subdomain was not required for ERAD-mediated passage of Cta1 from the ER to the cytosol.
Cholera Toxin Interactions with Host Cell Stress Proteins
The intrinsic conformational instability of the CTA1 polypeptide drives host-toxin interactions related to the translocation event and involves both standard and atypical functions for a variety of host chaperones.
Novel bacterial ADP-ribosylating toxins: structure and function
Bacterial ADP-ribosyltransferase toxins (bARTTs) transfer ADP-ribose to eukaryotic proteins to promote bacterial pathogenesis. In this Review, we use prototype bARTTs, such as diphtheria toxin and
Structural basis of actin recognition and arginine ADP-ribosylation by Clostridium perfringens ι-toxin
The crystal structure of actin-Ia in complex with the nonhydrolyzable NAD analog βTAD suggests a common reaction mechanism for ADPRTs and might be of use in rational drug design to block toxin-substrate recognition.
ADP‐ribosylation factor 6 acts as an allosteric activator for the folded but not disordered cholera toxin A1 polypeptide
It is found ARF6 prevents the thermal disordering of structured CTA1 and stimulates the activity of stabilized CTA 1 over a range of temperatures, yet ARF 6 alone did not promote the refolding of disordered CTA2 to an active state.
Contribution of subdomain structure to the thermal stability of the cholera toxin A1 subunit.
Observations provide mechanistic insight regarding the thermal unfolding of CTA1, an event which facilitates its subsequent translocation to the cytosol and the disordering of a Cta1 construct lacking the A1(3) subdomain.
The 1.8 Å Cholix Toxin Crystal Structure in Complex with NAD+ and Evidence for a New Kinetic Model
This crystal structure of cholix toxin with NAD+ reveals new insights into the reaction mechanism of this bacterial enzyme, and serves as a reference for continuing inhibitor development for this toxin class.


ARF binds the C-terminal region of the Escherichia coli heat-labile toxin (LTA1) and competes for the binding of LTA2.
The possibility that the LTA(2) subunit may function in cells as a partial ARF mimetic to compete for the binding of ARF to LTA (1) or regulate aspects of the toxin's transport from the cell surface to the ER is discussed.
Activation of Escherichia coli heat-labile enterotoxins by native and recombinant adenosine diphosphate-ribosylation factors, 20-kD guanine nucleotide-binding proteins.
Responsiveness to stimulation by ARF, GTP, and phospholipid/detergent as well as the specificity of ADP-ribosyltransferase activity are functions of LTs from serogroups LT-I and LT-II that are shared with cholera toxin.
Evolution and mechanism from structures of an ADP-ribosylating toxin and NAD complex
The crystal structure of the kinetically trapped VIP2–NAD complex identifies the NAD binding cleft within the C-terminal enzymatic domain and provides a structural basis for understanding the targeting and catalysis of the medically and environmentally important binary toxins.
Cholera toxin: A paradigm for multi-functional engagement of cellular mechanisms (Review)
The complexities of the cellular interactions that are engaged by these bacterial protein toxins are explored, and some of the new insights to have recently emerged are highlighted.
Crystal structures of an intrinsically active cholera toxin mutant yield insight into the toxin activation mechanism.
This work presents the first structural glimpse of an active CT in structures from three crystal forms of a single-site A-subunit CT variant, Y30S, and proposes a model for how the activational modifications experienced by wild-type CT are communicated to the active site.
Inhibitors of ADP-ribosylating bacterial toxins based on oxacarbenium ion character at their transition states.
Transition-state analogue interrogation of the bacterial toxins indicates that CTA gains catalytic efficiency from modest transition-state stabilization, but DTA and PTA catalyze ADP-ribosyl transferase reactions more from ground-state destabilization.
Crystal structure of a cholera toxin-related heat-labile enterotoxin from E. coli
This ADP-ribosylating (Al) fragment of the toxin has structural homology with the catalytic region of exotoxin A and hence also to diphtheria toxin.