Carotenogenesis of Staphylococcus aureus: New insights and impact on membrane biophysical properties

Abstract

Staphyloxanthin (STX) is a saccharolipid derived from a carotenoid in Staphylococcus aureus involved in oxidative-stress tolerance and antimicrobial peptide resistance. In this work, a targeted metabolomics and biophysical study was carried out on native and knock-out S. aureus strains to investigate the biosynthetic pathways of STX and related carotenoids. Identification of 34 metabolites at different growth phases (8, 24 and 48h), reveal shifts of carotenoid populations during progression towards stationary phase.Six of the carotenoids in the STX biosynthetic pathway and three menaquinones (Vitamin K2) were identified in the same chromatogram. Furthermore, other STX homologues with varying acyl chain structures reported herein for the first time, which reveal the extensive enzymatic activity of CrtO/CrtN. Fourier Transform infrared spectroscopy show that STX increases acyl chain order and shifts the cooperative melting of the membrane indicating a more rigid lipid bilayer. This study shows the diversity of carotenoids in S. aureus, and their influence on membrane biophysical properties.

Antibiofilm and staphyloxanthin inhibitory potential of terbinafine against Staphylococcus aureus: in vitro and in vivo studies

“…The decrease in S. aureus membrane fluidity has been linked to membrane staphyloxanthin content, elucidating the role of staphyloxanthin in regulating membrane stiffness [ 56 ]. FTIR analysis has been recently utilized for studying S. aureus membrane biophysical characters [ 57 ]. In the current study, the FTIR spectrum of terbinafine treated S. aureus showed changes in membrane lipids and polysaccharides comparable to untreated cells [ 29 ].…”

Staphylococcus aureus Carotenoids Modulate the Thermotropic Phase Behavior of Model Systems That Mimic Its Membrane Composition

“…A clinical methicillin-susceptible S. aureus strain was used, whose carotenoid chemical composition and its biophysical properties have been previously described [ 11 , 12 ]. A single colony of the strain was grown in 10 mL of LB medium at 37 °C overnight (16 h) with constant agitation (250 rpm).…”

“…The extraction of carotenoids was achieved using a method previously reported by López et al, with some modifications [ 12 ]. A gram of freeze-dried and grounded cells (with mortar and pestle) was weighed in a Falcon tube and dissolved in 20 mL of methanol (MeOH) containing BHT at 0.1%, w / v ; then, 20 glass beads were added and vortex-mixed for 5 min.…”

“…Then, the organic phase was dried with anhydrous Na 2 SO 4 , transferred to an amber tube, and finally dried with a CentriVap refrigerated vacuum concentrator (LABCONCO, Kansas City, MO, USA). The composition of the extract was confirmed using LC-MS/MS method with the conditions previously reported [ 12 ].…”

“…Carotenoids are associated with tolerance to oxidative stress and regulation of the mechanical properties of the bacterial membrane [ 9 , 10 , 11 ]. Recently, a composition of total carotenoids from S. aureus at 24 h of growth has been reported, which was made up of two identified compounds: 4,4’-diaponeuresporenoic acid and staphyloxanthin (STX) (including its homologues) [ 12 , 13 ], both related to the increase in the virulence and bacterial fitness of S. aureus [ 14 , 15 ]. In a previous publication, it has been shown that carotenoid production depends on growth conditions, where carotenoids are synthesized in large quantities in the stationary phase but are not present in the exponential phase or in biofilms grown under flow conditions in the dark [ 11 ].…”