Proteomic analysis of ethanol reduced susceptibility mutants
Abstract
Staphylococcus aureus are dangerous pathogens responsible for thousands of deaths every year, and it is estimated that 95 million Americans may be carriers of a S. aureus strain (1). Even more dangerous is the subset of Multiple Resistant Staphylococcus aureus (MRSA). MRSA commonly cause nosocomial infections, but the prevalence of MRSA in the community is increasing. The use of alcohol-based hand rubs (ABHR) has greatly increased hand hygiene compliance and convenience to combat hand carriage of S. aureus. To study the effects of alcohol as a selective pressure on the bacteria, the Gustafson laboratory passaged Methicillin susceptible S. aureus strain SH1000 through up to 12% ethanol and conducted proteomic analysis of isolated ethanol reduced susceptibility SH1000 mutants SH123 and SH124. Concentrations of proteins associated with multiple notable systems were found altered: iron acquisition and autolysis proteins were increased, while proteins associated with purine biosynthesis, virulence, and an alcohol dehydrogenase were present in decreased concentrations in the mutants. Autolysins may function to remove peptidoglycan damaged by ethanol during exposure to the biocide. I hypothesize that the increased autolysin concentrations in the mutants are leading to iron leakage secondary to cell wall breakdown, resulting in increased need for siderophores and iron transporters. In addition, I hypothesize that the decrease of other system proteins is explained by the slow growth phenotype resulting in a lower energy demand and conservation of resources through reducing non-vital functions.