<i>Staphylococcus aureus</i> CidC Is a Pyruvate:Menaquinone Oxidoreductase

Published on 2018-03-13T15:18:33Z (GMT) by
Recent studies have revealed an important role for the <i>Staphylococcus aureus</i> CidC enzyme in cell death during the stationary phase and in biofilm development and have contributed to our understanding of the metabolic processes that are important in the induction of bacterial programmed cell death (PCD). To gain more insight into the characteristics of this enzyme, we performed an in-depth biochemical and biophysical analysis of its catalytic properties. <i>In vitro</i> experiments show that this flavoprotein catalyzes the oxidative decarboxylation of pyruvate to acetate and carbon dioxide. CidC efficiently reduces menadione, but not CoenzymeQ<sub>0</sub>, suggesting a specific role in the <i>S. aureus</i> respiratory chain. CidC exists as a monomer under neutral-pH conditions but tends to aggregate and bind to artificial lipid membranes at acidic pH, resulting in enhanced enzymatic activity. Unlike its <i>Escherichia coli</i> counterpart, PoxB, CidC does not appear to be activated by other amphiphiles like Triton X-100 or octyl β-d-glucopyranoside. In addition, only reduced CidC is protected from proteolytic cleavage by chymotrypsin, and unlike its homologues in other bacteria, protease treatment does not increase CidC enzymatic activity. Finally, CidC exhibits maximal activity at pH 5.5–5.8 and negligible activity at pH 7–8. The results of this study are consistent with a model in which CidC functions as a pyruvate:menaquinone oxidoreductase whose activity is induced at the cellular membrane during cytoplasmic acidification, a process previously shown to be important for the induction of bacterial PCD.

Cite this collection

Zhang, Xinyan; Bayles, Kenneth W.; Luca, Sorin (2018): Staphylococcus aureus CidC Is a Pyruvate:Menaquinone

Oxidoreductase. ACS Publications.