Nanobodies against C. difficile TcdA and TcdB reveal unexpected neutralizing epitopes and provide a toolkit for toxin quantitation in vivo.

Clostridioides difficile is a leading cause of antibiotic-associated diarrhea and nosocomial infection in the United States. The symptoms of C. difficile infection (CDI) are associated with the production of two homologous protein toxins, TcdA and TcdB.

The USP46 complex deubiquitylates LRP6 to promote Wnt/β-catenin signaling.

The relative abundance of Wnt receptors plays a crucial role in controlling Wnt signaling in tissue homeostasis and human disease. While the ubiquitin ligases that ubiquitylate Wnt receptors are well-characterized, the deubiquitylase that reverses these reactions remains unclear. Herein, we identify USP46, UAF1, and WDR20 (USP46 complex) as positive regulators of Wnt signaling in cultured human cells.

Murine Intrarectal Instillation of Purified Recombinant Toxins Enables Mechanistic Studies of Pathogenesis.

is linked to nearly 225,000 antibiotic-associated diarrheal infections and almost 13,000 deaths per year in the United States. Pathogenic strains of produce toxin A (TcdA) and toxin B (TcdB), which can directly kill cells and induce an inflammatory response in the colonic mucosa. Hirota et al.

Specificity and affinity of the N-terminal residues in staphylocoagulase in binding to prothrombin.

In -caused endocarditis, the pathogen secretes staphylocoagulase (SC), thereby activating human prothrombin (ProT) and evading immune clearance. A previous structural comparison of the SC(1-325) fragment bound to thrombin and its inactive precursor prethrombin 2 has indicated that SC activates ProT by inserting its N-terminal dipeptide Ile-Val into the ProT Ile pocket, forming a salt bridge with ProT's Asp, thereby stabilizing the active conformation. We hypothesized that these N-terminal SC residues modulate ProT binding and activation.

Intestinal bile acids directly modulate the structure and function of TcdB toxin.

Intestinal bile acids are known to modulate the germination and growth of Here we describe a role for intestinal bile acids in directly binding and neutralizing TcdB toxin, the primary determinant of disease. We show that individual primary and secondary bile acids reversibly bind and inhibit TcdB to varying degrees through a mechanism that requires the combined oligopeptide repeats region to which no function has previously been ascribed. We find that bile acids induce TcdB into a compact "balled up" conformation that is no longer able to bind cell surface receptors.