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A genetically encoded photosensitizer


Photosensitizers are chromophores that generate reactive oxygen species (ROS) upon light irradiation1. They are used for inactivation of specific proteins by chromophore-assisted light inactivation (CALI) and for light-induced cell killing in photodynamic therapy. Here we report a genetically encoded photosensitizer, which we call KillerRed, developed from the hydrozoan chromoprotein anm2CP, a homolog of green fluorescent protein (GFP). KillerRed generates ROS upon irradiation with green light. Whereas known photosensitizers must be added to living systems exogenously, KillerRed is fully genetically encoded. We demonstrate the utility of KillerRed for light-induced killing of Escherichia coli and eukaryotic cells and for inactivating fusions to β-galactosidase and phospholipase Cδ1 pleckstrin homology domain.

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We are grateful to Alexei V. Feofanov for valuable advice and help in light intensity measurements. This work was supported by Howard Hughes Medical Institute grant HHMI 55005618, the Russian Academy of Sciences for the program “Molecular and Cell Biology” and the EC FP-6 Integrated Project LSHG-CT-2003-503259.

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The authors declare no competing financial interests.

Correspondence to Konstantin A Lukyanov.

Supplementary information

Supplementary Fig. 1

Absorption spectra of and superoxide generation by intact and prebleached KillerRed protein. (PDF 92 kb)

Supplementary Data (PDF 62 kb)

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Figure 1: Identification and characterization of the phototoxic properties of KillerRed.
Figure 2: Light-induced killing of eukaryotic cells expressing KillerRed.
Figure 3: KillerRed-mediated light-induced inactivation of the PLC δ1 PH domain.