Clostridium difficile glutamate dehydrogenase is a secreted enzyme that confers resistance to H2O2

Abstract

Clostridium difficile produces an NAD-specific glutamate dehydrogenase (GDH), which converts L-glutamate into a-ketoglutarate through an irreversible reaction. The enzyme GDH is detected in the stool samples of patients with C. difficile-associated disease and serves as one of the diagnostic tools to detect C. difficile infection (CDI). We demonstrate here that supernatant fluids of C. difficile cultures contain GDH. To understand the role of GDH in the physiology of C. difficile, an isogenic insertional mutant of gluD was created in strain JIR8094. The mutant failed to produce and secrete GDH as shown by Western blot analysis. Various phenotypic assays were performed to understand the importance of GDH in C. difficile physiology. In TY (tryptose yeast extract) medium, the gluD mutant grew slower than the parent strain. Complementation of the gluD mutant with the functional gluD gene reversed the growth defect in TY medium. The presence of extracellular GDH may have a functional role in the pathogenesis of CDI. In support of this assumption we found higher sensitivity to H 2 O 2 in the gluD mutant as compared to the parent strain. Complementation of the gluD mutant with the functional gluD gene reversed the H 2 O 2 sensitivity.

Mass Spectrometric Analysis of Whole Secretome and Amylase-precipitated Secretome Proteins from Streptococcus gordonii

“…It has been shown that glutamate dehydrogenase functions in providing resistance to stress in yeast cells [ 24 ]. In Clostridium difficile , extracellular glutamate dehydrogenase was found to confer resistance to hydrogen peroxide [ 25 ]. Metal-binding (Mn) permease lipoproteins may act as surface ligands for host cell matrix proteins [ 26 ].…”

Proteomic analysis on the antibacterial activity of a Ru(II) complex against Streptococcus pneumoniae

“…In addition, based on the GO analysis, 3-ketoacyl-(acyl-carrier-protein) reductase (FabG) and glutamate dehydrogenase (GhdA) possess the oxidoreductase activity to produce reduced nicotinamide-adenine dinucleotide phosphate (NADPH). Studies on Clostridium difficile have suggested that GhdA contributes to oxidative stress resistance [20]. Moreover, the down-regulated oxidoreductase, aldo/keto reductase family protein (SPD_0693) and oxidoreductase, Gfo/Idh/MocA family protein (SPD_1311) also were predicted to have NADP binding domain.…”

The alternative sigma factor σB plays a crucial role in adaptive strategies of Clostridium difficile during gut infection

“…Although the role of these proteins in ROS detoxification remains to be experimentally characterised in C. difficile, it seems likely that the control of their transcription by r B contributes to the increased sensitivity of the sigB mutant to ROS exposure. In addition, the expression of gluD, encoding a glutamate dehydrogenase that is involved in C. difficile in H 2 O 2 protection via an uncharacterised mechanism, also decreased three-fold in the sigB mutant (Girinathan et al, 2014).…”