%0 artículo %A Guzman-Verri, Caterina %E Quesada-Gómez, Carlos %E López-Ureña, Diana %E Chumbler, Nicole %E Kroh, Heather %E Castro-Peña, Carolina %E Rodríguez, César %E Orozco-Aguilar, Josué %E González-Camacho, Sara %E Rucavado, Alexandra %E Lawley, Trevor %E Lacy, D. Borden %E Chaves-Olarte, Esteban %D 2016 %G eng %T Analysis of TcdB proteins within the hypervirulent clade 2 reveals an impact of RhoA glucosylation on Clostridium difficile proinflammatory activities %U http://hdl.handle.net/11056/17573 %X Clostridium difficile strains within the hypervirulent clade 2 are responsible for nosocomial outbreaks worldwide. The increased pathogenic potential of these strains has been attributed to several factors but is still poorly understood. During a C. difficile outbreak, a strain from this clade was found to induce a variant cytopathic effect (CPE), different from the canonical arborizing CPE. This strain (NAP1V) belongs to the NAP1 genotype but to a ribotype different from the epidemic NAP1/RT027 strain. NAP1V and NAP1 share some properties, including the overproduction of toxins, the binary toxin, and mutations in tcdC. NAP1V is not resistant to fluoroquinolones, however. A comparative analysis of TcdB proteins from NAP1/RT027 and NAP1V strains indicated that both target Rac, Cdc42, Rap, and R-Ras but only the former glucosylates RhoA. Thus, TcdB from hypervirulent clade 2 strains possesses an extended substrate profile, and RhoA is crucial for the type of CPE induced. Sequence comparison and structural modeling revealed that TcdBNAP1 and TcdBNAP1V share the receptor-binding and autoprocessing activities but vary in the glucosyltransferase domain, consistent with the different substrate profile. Whereas the two toxins displayed identical cytotoxic potencies, TcdBNAP1 induced a stronger proinflammatory response than TcdBNAP1V as determined in ex vivo experiments and animal models. Since immune activation at the level of intestinal mucosa is a hallmark of C. difficile-induced infections, we propose that the panel of substrates targeted by TcdB is a determining factor in the pathogenesis of this pathogen and in the differential virulence potential seen among C. difficile strains.