Where metabolism and virulence meet—sulfoxide reductases as determinants of bacterial survival

Abstract

Bacterial metabolism is increasingly recognised as a driver of virulence in pathogens, and this includes the reduction of sulfoxides, which has traditionally been linked to anaerobic energy generation and maintenance of cellular proteins. Sulfoxide reduction is catalysed by two major enzyme groups, the Msr peptide methionine sulfoxide reductases that repair damaged proteins, and several types of mononuclear molybdenum enzymes that either convert small molecular S- and N-oxides or repair damaged proteins. Where these enzymes support virulence, they appear to be regulated by exposure to oxidising stressors such as hypochlorite and are often required for hypochlorite resistance and successful host interactions, either by maintaining the integrity of proteins or repairing damage to nutrient molecules such as amino acids and vitamins. As the virulence-supporting S- and N-oxide reductases retain their original architecture and links to metabolic processes, so that their action often also contributes to cellular redox balancing, energy generation, and access to specific nutrients, all of which support in-host survival.