difficile infection is invariably associated with the disruption

difficile infection is invariably associated with the disruption of the normal intestinal microflora by the administration of broad spectrum antibiotics. Thus there is a pressing need to develop therapies that selectively target C. difficile while leaving the intestinal microflora intact. The C. difficile reference strain 630 encodes a single predicted sortase, CD630_27180, which has strong amino acid similarity with SrtB of S. aureus PP2 nmr and B. anthracis

[24]. Sortase substrates frequently contribute toward pathogenesis via their involvement in attachment to specific tissues during infection [17,41–44], as well as the bacteria’s ability to evade the immune response of the host [32,36]. Sortases, although not essential for growth or viability of the organism, are often essential for virulence in Gram-positive organisms; inactivation of sortases reduces colonization in mice [8,13,44,45], and decreases adhesion and invasion in vitro [8,10,14,46,47]. Sortases and their substrates are considered promising targets

for the development of new anti-infective compounds [10,14,48]. Unusually for Gram-positive bacteria, C. difficile appears to possess a single sortase enzyme that is likely to be important for the viability of the pathogen as we have been unable to construct a C. difficile strain 630 SrtB defined mutant (unpublished data). Inhibiting the C. difficile sortase could prove to be a strategy to specifically target C. difficile. In this study, we cloned, expressed and characterized the sortase encoded by CD630_27180 learn more of C. difficile 630, a predicted class B sortase (SrtB). Sortase nomenclature is based on sequence similarity to the known classes of sortase, A-F [7]. Sortases of class B typically are involved in heme-iron uptake and tend to be expressed in operons with their substrates [17,18]. Genes encoding class A sortases are not found in proximity to their substrates, which consist of a variety of surface proteins with diverse biological MK 8931 solubility dmso functions. Several selleck chemicals exceptions to these rules have already

been described, notably a class B sortase that polymerizes pilin subunits in S. pyogenes [49], and a class E sortase from C. diphtheriae that serves a housekeeping function [50]. The potential C. difficile sortase substrates identified in this paper comprise a diverse range of surface proteins, suggesting that SrtB may serve as a housekeeping sortase in C. difficile, a function usually reserved for class A sortases. These potential sortase substrates in C. difficile strain 630 comprise of seven proteins, all containing an (S/P)PXTG motif, that are predicted to be surface localized and are conserved across C. difficile strains. Recently it was proposed that a C. difficile collagen binding protein, CbpA, may be sorted to the cell surface by sortase recognizing an NVQTG motif [30]. In this study, we developed a FRET-based assay to demonstrate that SrtB of C.

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