These authors contributed equally to this work.
Photodynamic oxidation of Staphylococcus warneri membrane phospholipids: new insights based on lipidomics
Article first published online: 14 JUN 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Rapid Communications in Mass Spectrometry
Volume 27, Issue 14, pages 1607–1618, 30 July 2013
How to Cite
Alves, E., Melo, T., Simões, C., Faustino, M. A. F., Tomé, J. P. C., Neves, M. G. P. M. S., Cavaleiro, J. A. S., Cunha, Â., Gomes, N. C. M., Domingues, P., Domingues, M. R. M. and Almeida, A. (2013), Photodynamic oxidation of Staphylococcus warneri membrane phospholipids: new insights based on lipidomics. Rapid Commun. Mass Spectrom., 27: 1607–1618. doi: 10.1002/rcm.6614
- Issue published online: 10 JUN 2013
- Article first published online: 14 JUN 2013
- Manuscript Accepted: 28 APR 2013
- Manuscript Revised: 17 APR 2013
- Manuscript Received: 11 JAN 2013
The photodynamic process involves the combined use of light and a photosensitizer, which, in the presence of oxygen, originates cytotoxic species capable of oxidizing biological molecules, such as lipids. However, the effect of the photodynamic process in the bacterial phospholipid profile by a photosensitizer has never been reported. A lipidomic approach was used to study the photodynamic oxidation of membrane phospholipids of Staphylococcus warneri by a tricationic porphyrin [5,10,15-tris(1-methylpyridinium-4-yl)-20-(pentafluorophenyl)porphyrin triiodide, Tri-Py+-Me-PF].
S. warneri (108 colony forming units mL–1) was irradiated with white light (4 mW cm–2, 21.6 J cm–2) in the presence of Tri-Py+-Me-PF (5.0 μM). Non-photosensitized bacteria were used as control (irradiated without porphyrin). After irradiation, total lipids were extracted and separated by thin-layer chromatography (TLC). Isolated fractions of lipid classes were quantified by phosphorus assay and analyzed by mass spectrometry (MS): off-line TLC/ESI-MS, hydrophilic interaction (HILIC)-LC/MS and MS/MS.
The most representative classes of S. warneri phospholipids were identified as phosphatidylglycerols (PGs) and cardiolipins (CLs). Lysyl-phosphatidylglycerols (LPGs), phosphatidylethanolamines (PEs), phosphatidylcholines (PCs) and phosphatidic acids (PAs) were also identified. After photodynamic treatment, an overall increase in the relative abundance of PGs was observed as well as the appearance of new oxidized species from CLs, including hydroxy and hydroperoxy derivatives. Formation of high amounts of lipid hydroperoxides was confirmed by FOX2 assay. Photodynamic oxidation of phospholipid standards revealed the formation of hydroperoxy and dihydroperoxy derivatives, confirming the observed CL oxidized species in S. warneri.
Membrane phospholipids of S. warneri are molecular targets of the photoinactivation process induced by Tri-Py+-Me-PF. The overall modification in the relative amount of phospholipids and the formation of lipid hydroxides and hydroperoxides indicate the lethal damage caused to photosensitized bacterial cells. Copyright © 2013 John Wiley & Sons, Ltd.