Stable Transfection of the Singlet Oxygen Photosensitizing Protein SOPP3: Examining Aspects of Intracellular Behavior. (22nd May 2021)

• Record Type: Journal Article
• Authors: Mogensen, Ditte J.; Westberg, Michael; Breitenbach, Thomas; Etzerodt, Michael; Ogilby, Peter R.
• Is Part Of: Photochemistry and photobiology. Volume 97:Number 6(2021)
• Page Start: 1417
• Page End: 1430
• Publication Date: 2021-05-22
• Subjects: Photochemistry -- Periodicals; Light -- Physiological effect -- Periodicals; 541.35
• DOI: 10.1111/php.13440
• Languages: English
• ISSNs: 0031-8655

Abstract

Abstract: Protein‐encased chromophores that photosensitize the production of reactive oxygen species, ROS, have been the center of recent activity in studies of oxidative stress. One potential attribute of such systems is that the local environment surrounding the chromophore, and that determines the chromophore's photophysics, ideally remains constant and independent of the global environment into which the system is placed. Therefore, a protein‐encased sensitizer localized in the mitochondria would arguably have the same photophysics as that protein‐encased sensitizer at the plasma membrane, for example. One thus obtains a useful tool to study processes modulated by spatially localized ROS. One ROS of interest is singlet oxygen, O2 (a 1 Δg ). We recently developed a singlet oxygen photosensitizing protein, SOPP, in which flavin mononucleotide, FMN, is encased in a re‐engineered light‐oxygen‐voltage protein. One goal was to ascertain how a version of this system, SOPP3, which selectively makes O2 (a 1 Δg ), in vitro, behaves in a cell. We now demonstrate that SOPP3 undergoes exacerbated irradiation‐mediated bleaching when expressed at either the plasma membrane or mitochondria in stable cell lines. We find that the environment around the SOPP3 system affects the bleaching rate, which argues against one of the key suppositions in support of a protein‐encased chromophore. Abstract : A protein‐encased singlet oxygen sensitizer bleaches more rapidly when localized in a mammalian cell than when dissolved in an aqueous medium. Other proteins in the surrounding environment increase the bleaching rate of the encased sensitizer, presumably via electron transfer reactions.