Characterisation of the manganese superoxide dismutase of Enterococcus faecium

The manganese superoxide dismutase (SodA) of E. faecium strain AUS0004 has been characterised. It is most closely related to Enterococcus hirae, Enterococcus durans, Enterococcus villorium, and Enterococcus mundtii with 100%, 91,55%, 90,85%, and 90,58% homology, respectively, but more distant from SodA of E. faecalis (81.68%). A sodA deletion mutant has been constructed. Compared to the parental strain, the Delta sodA mutant was affected in aerobic growth and more sensitive to hydrogen peroxide (H2O2), cumene hydroperoxide (CuOOH), and the superoxide anion cumene hydroperoxide (CuOOH), and the superoxide anion (O-2 center dot(-)) generator menadione. The E. faecium strain AUS0004 is part of those bacteria accumulating H2O2 to high concentrations (around 5 mM) starting from late exponential growth phase. Accumulation of the peroxide was around 25% less in the mutant suggesting that this part of H2O2 is due to the dismutation of O-2 center dot(-) by SodA. The sodA gene of E. faecium AUS0004 was induced by oxygen, peroxides and menadione but the corresponding regulator remains hitherto unknown. Finally, we showed that SodA activity is important for virulence in the Galleria mellonella model. (C) 2021 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Automated summary

The study characterized the SodA gene of E. faecium strain AUS0004, showing its importance in response to oxygen, peroxides, and menadione, and its role in bacterial oxidative stress and virulence.