Tiwari, K.B.; Gatto, C.; Wilkinson, B.J. Interrelationships between Fatty Acid Composition, Staphyloxanthin Content, Fluidity, and Carbon Flow in the Staphylococcus aureus Membrane. Molecules2018, 23, 1201.
Tiwari, K.B.; Gatto, C.; Wilkinson, B.J. Interrelationships between Fatty Acid Composition, Staphyloxanthin Content, Fluidity, and Carbon Flow in the Staphylococcus aureus Membrane. Molecules 2018, 23, 1201.
Fatty acids play a major role in determining membrane biophysical properties. Staphylococcus aureus produces branched-chain fatty acids (BCFAs) and straight-chain fatty acids (SCFAs), and can incorporate exogenous SCFAs and straight-chain unsaturated fatty acids (SCUFAs). Many S. aureus strains produce the triterpenoid pigment staphyloxanthin, and the balance of BCFAs, SCFAs and staphyloxanthin determines membrane fluidity. Here, we investigated the relationship of fatty acid and carotenoid production in S. aureus using a pigmented strain (Pig1), its carotenoid-deficient mutant (Pig1ΔcrtM) and the naturally non-pigmented Staphylococcus argenteus that lacks carotenoid biosynthesis genes and is closely related to S. aureus. Fatty acid compositions in all strains were similar under a given condition indicating that staphyloxanthin does not influence fatty acid composition. Strain Pig1 had decreased membrane fluidity as measured by fluorescence anisotropy than the other strains under all conditions indicating that staphyloxanthin helps maintain membrane rigidity. We could find no evidence for correlation of expression of crtM and fatty acid biosynthesis genes. Supplementation of medium with glucose increased SCFA production and decreased BCFA and staphyloxanthin production, whereas acetate-supplementation also decreased BCFAs but increased staphyloxanthin production. We believe that staphyloxanthin levels are influenced more through metabolic regulation than responding to fatty acids incorporated into the membrane.
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