Abstract
Bacterial DsbA enzymes catalyze oxidative folding of virulence factors, and have been identified as targets for antivirulence drugs. However, DsbA enzymes characterized to date exhibit a wide spectrum of redox properties and divergent structural features compared to the prototypical DsbA enzyme of Escherichia coli DsbA (EcDsbA). Nonetheless, sequence analysis shows that DsbAs are more highly conserved than their known substrate virulence factors, highlighting the potential to inhibit virulence across a range of organisms by targeting DsbA. For example, Salmonella enterica typhimurium (SeDsbA, 86 % sequence identity to EcDsbA) shares almost identical structural, surface and redox properties. Using comparative sequence and structure analysis we predicted that five other bacterial DsbAs would share these properties. To confirm this, we characterized Klebsiella pneumoniae DsbA (KpDsbA, 81 % identity to EcDsbA). As expected, the redox properties, structure and surface features (from crystal and NMR data) of KpDsbA were almost identical to those of EcDsbA and SeDsbA. Moreover, KpDsbA and EcDsbA bind peptides derived from their respective DsbBs with almost equal affinity, supporting the notion that compounds designed to inhibit EcDsbA will also inhibit KpDsbA. Taken together, our data show that DsbAs fall into different classes; that DsbAs within a class may be predicted by sequence analysis of binding loops; that DsbAs within a class are able to complement one another in vivo and that compounds designed to inhibit EcDsbA are likely to inhibit DsbAs within the same class.
Highlights
Antibiotic resistance has increased dramatically over the last decade and the consequent lack of treatment options poses a major threat for public health [1]
We investigated two well-characterised DsbAs sharing 86% sequence identity, from E. coli K-12 strain (EcDsbA) and S. enterica Typhimurium DsbA strain SL1344 (SeDsbA), by applying comparative structural, sequence and redox analyses to identify properties conserved across these two enzymes
To assess whether the redox and structural properties are maintained in this DsbA group we focused on KpDsbA, which shares the lowest sequence identity with Escherichia coli DsbA (EcDsbA)
Summary
Antibiotic resistance has increased dramatically over the last decade and the consequent lack of treatment options poses a major threat for public health [1]. One approach to develop new chemical classes of antibacterials is to target virulence factors that cause disease in antibiotic resistant organisms [2]. The inner membrane protein DsbB, in concert with its cofactor ubiquinone, interacts with reduced DsbA to oxidize the active site cysteines and convert DsbA to its functionally competent disulfide form [10]. Inhibition of the interaction between DsbA and substrate proteins or between DsbA and its partner DsbB could constitute a means of blocking virulence factor formation and thereby of inhibiting virulence of bacterial pathogens. Supporting this notion, deletion of DsbA homologues in
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