Comparative Transcriptomics Reveals Discrete Survival Responses ofS. aureusandS. epidermidisto Sapienic Acid.
Staphylococcal colonization of human skin is ubiquitous, with particular species more frequent at different body sites. WhereasStaphylococcus epidermidiscan be isolated from the skin of every individual tested,Staphylococcus aureusis isolated from <5% of healthy individuals. The factors that drive staphylococcal speciation and niche selection on skin are incompletely defined. Here we show thatS. aureusis inhibited to a greater extent thanS. epidermidisby the sebaceous lipid sapienic acid, supporting a role for this skin antimicrobial in selection of skin staphylococci. We used RNA-Seq and comparative transcriptomics to identify the sapienic acid survival responses ofS. aureusandS. epidermidis. Consistent with the membrane depolarization mode of action of sapienic acid, both species shared a common transcriptional response to counteract disruption of metabolism and transport. The species differed in their regulation of SaeRS and VraRS regulons. WhileS. aureusupregulated urease operon transcription,S. epidermidisupregulated arginine deiminase, the oxygen-responsive NreABC nitrogen regulation system and the nitrate and nitrite reduction pathways. The role ofS. aureusACME and chromosomal arginine deiminase pathways in sapienic acid resistance was determined through mutational studies. We speculate that ammonia production could contribute to sapienic acid resistance in staphylococci.
Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool Liverpool, UK.
Josephine C
JC
Moran
Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool Liverpool, UK.
Jamal A
JA
Alorabi
Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool Liverpool, UK.
Malcolm J
MJ
Horsburgh
RNA-Seq; Staphylococcus aureus; Staphylococcus epidermidis; colonization; fatty acid; sapienic acid; skin