Oleate Hydratase (OhyA) Is a Virulence Determinant in Staphylococcus aureus

Abstract

The oleate hydratase protein family was discovered in commensal bacteria that utilize host unsaturated fatty acids as the substrates to produce a spectrum of hydroxylated products. These hydroxy fatty acids are thought to act as signaling molecules that suppress the inflammatory response to create a more tolerant environment for the microbiome. S. aureus is a significant human pathogen, and defining the mechanisms used to evade the immune response is critical to understanding pathogenesis. S. aureus expresses an OhyA that produces at least three 10-hydroxy fatty acids from host unsaturated fatty acids at the infection site, and an S. aureus strain lacking the ohyA gene has compromised virulence in an immunocompetent infection model.

The Phospholipase A1 Activity of Glycerol Ester Hydrolase (Geh) Is Responsible for Extracellular 2-12( S )-Methyltetradecanoyl-Lysophosphatidylglycerol Production in Staphylococcus aureus

“…These results were validated by constructing strain PDJ171 (Δ geh ), a derivative of wild-type strain AH1263 that was constructed to contain an unmarked deletion of the geh gene coding sequence ( 20 ). The production of extracellular a15-LPG was measured in strains AH1263/pPJ480, PDJ171 (Δ geh )/pPJ480 containing the empty vector, and strain PDJ171 (Δ geh )/pGeh programed to express geh driven by the sarA promoter ( Table S1 ).…”

“…The geh gene was amplified by PCR using primers designed for Gibson Assembly cloning into NdeI and HindIII digested pET28a to obtain pPJ628 with a carboxy-terminal His tag used for E. coli expression and purification of proGeh and mGeh. These His-tagged constructs were then cloned into pPJ480 at the NcoI and HindIII sites to derive plasmid pPJ630 for expression in S. aureus driven by the sarA promoter ( 20 ). Plasmids were rendered transformable into normal S. aureus strains by passing them through strain RN4220.…”

“…The transcription of the geh gene depends on the activity of the Agr quorum-sensing signal transduction system that acts as a master regulator of S. aureus virulence factor transcription ( 12 ). Geh has a role in virulence based on its hydrolysis of host lipids at the infection site to provide fatty acids for membrane biogenesis ( 15 to 18 ), substrates for oleate hydratase ( 19 , 20 ), and by hydrolyzing lipoprotein glycerol esters to attenuate immune cell activation ( 21 ). The primary geh translation product is preproGeh, and the 37-residue signal sequence is removed concomitant with its transport out of the cell ( 22 ).…”

Transcriptomic and Metabolomic Analysis of a Fusidic Acid-Selected fusA Mutant of Staphylococcus aureus

“…The most highly downregulated gene in SH10001st-2 encodes an iron compound transporter, SmpB ( Table 5 ), and there were 9 iron/heme transport-associated genes that were upregulated (e.g., isdC , isdG , srtB , and heme permeases) ( Table S1 and Table 5 ). A gene encoding oleate hydratase, which is a virulence factor that promotes immune evasion by modifying host fatty acids provided by secreted lipases [ 27 ], was also downregulated ( Table 5 ). We note that these gene expression patterns were inconsistent with a strictly upregulated virulence response interpretation.…”

Towards an understanding of oleate hydratases and their application in industrial processes

“…The hydroxylated form does not further convey toxicity and is not incorporated into the phospholipid membrane but is rather exported into the outer environment [ 13 ]. Recently, it was shown that OhySa are able to convert host cis - 9 unsaturated fatty acids to their 10-hydroxy derivatives in human serum and at the infection site in a mouse neutropenic thigh model, suggesting that OhySa could play a role in immune modulation in S. aureus pathogenesis [ 14 ]. Furthermore, fatty acid hydratases have been reported to be involved in stress responses of microorganisms.…”