Laboratory of Advanced Analytical Techniques in Natural Products (LATNAP), Chemistry Department, Universidad de los Andes, Bogotá D.C., Colombia; Laboratory of Biophysics, Physics Department, Universidad de los Andes, Bogotá D.C., Colombia; Laboratory of Foodomics, Institute of Food Science Research, CIAL, CSIC, Madrid, Spain.
Laboratory of Biophysics, Physics Department, Universidad de los Andes, Bogotá D.C., Colombia.
Biochim Biophys Acta Mol Cell Biol Lipids. 2021 Aug;1866(8):158941. doi: 10.1016/j.bbalip.2021.158941. Epub 2021 Apr 13.
Staphyloxanthin (STX) is a saccharolipid derived from a carotenoid in Staphylococcus aureus involved in oxidative-stress tolerance and antimicrobial peptide resistance. STX influences the biophysical properties of the bacterial membrane and has been associated to the formation of lipid domains in the regulation of methicillin-resistance. In this work, a targeted metabolomics and biophysical characterization study was carried out to investigate the biosynthetic pathways of carotenoids, and their impact on the membrane biophysical properties. Five different S. aureus strains were investigated, including three wild-type strains containing the crtM gene related to STX biosynthesis, a crtM-deletion mutant, and a crtMN plasmid-complemented variant. LC-DAD-MS/MS analysis of extracts allowed the identification of 34 metabolites related to carotenogenesis in S. aureus at different growth phases (8, 24 and 48 h), showing the progression of these metabolites as the bacteria advances into the stationary phase. For the first time, 22 members of a large family of carotenoids were identified, including STX and STX-homologues, as well as Dehydro-STX and Dehydro-STX-homologues. Moreover, thermotropic behavior of the CH stretch of lipid acyl chains in live cells by FTIR, show that the presence of STX increases acyl chain order at the bacterial growth temperature. Indeed, the cooperative melting event of the bacterial membrane, which occurs around 15 °C in the native strains, shifts with increased carotenoid content. These results show the diversity biosynthetic of carotenoids in S. aureus, and their influence on membrane biophysical properties.
金黄色素（STX）是一种来源于金黄色葡萄球菌类胡萝卜素的糖脂，参与氧化应激耐受和抗抗菌肽抗性。STX 影响细菌膜的生物物理特性，并与耐甲氧西林的形成有关。在这项工作中，进行了靶向代谢组学和生物物理特性研究，以研究类胡萝卜素的生物合成途径及其对膜生物物理特性的影响。研究了五种不同的金黄色葡萄球菌菌株，包括三种含有与 STX 生物合成相关的 crtM 基因的野生型菌株、crtM 缺失突变体和 crtMN 质粒互补变体。提取物的 LC-DAD-MS/MS 分析允许鉴定 34 种与金黄色葡萄球菌不同生长阶段（8、24 和 48 小时）的类胡萝卜素生物合成相关的代谢物，表明随着细菌进入静止期，这些代谢物的进展。首次鉴定了一个大型类胡萝卜素家族的 22 个成员，包括 STX 和 STX 类似物，以及 Dehydro-STX 和 Dehydro-STX 类似物。此外，FTIR 通过活细胞中 CH 伸缩的热物性研究表明，STX 的存在增加了细菌生长温度下的酰基链有序性。事实上，在天然菌株中，在 15°C 左右发生的细菌膜协同熔融事件随着类胡萝卜素含量的增加而发生变化。这些结果表明金黄色葡萄球菌中类胡萝卜素的生物合成多样性及其对膜生物物理特性的影响。
