Structural basis for phototoxicity of the genetically encoded photosensitizer KillerRed

Sergei Pletnev, Nadya G. Gurskaya, Nadya V. Pletneva, Konstantin A. Lukyanov, Dmitri M. Chudakov, Vladimir I. Martynov, Vladimir O. Popov, Mikhail V. Kovalchuk, Alexander Wlodawer, Zbigniew Dauter, Vladimir Pletnev

Research output: Contribution to journalArticlepeer-review

106 Citations (Scopus)


KillerRed is the only known fluorescent protein that demonstrates notable phototoxicity, exceeding that of the other green and red fluorescent proteins by at least 1,000-fold. KillerRed could serve as an instrument to inactivate target proteins or to kill cell populations in photodynamic therapy. However, the nature of KillerRed phototoxicity has remained unclear, impeding the development of more phototoxic variants. Here we present the results of a high resolution crystallographic study of KillerRed in the active fluorescent and in the photobleached non-fluorescent states. A unique and striking feature of the structure is a water-filled channel reaching the chromophore area from the end cap of the β-barrel that is probably one of the key structural features responsible for phototoxicity. A study of the structure-function relationship of KillerRed, supported by structure-based, site-directed mutagenesis, has also revealed the key residues most likely responsible for the phototoxic effect. In particular, Glu68 and Ser119, located adjacent to the chromophore, have been assigned as the primary trigger of the reaction chain.

Original languageEnglish
Pages (from-to)32028-32039
Number of pages12
JournalJournal of Biological Chemistry
Issue number46
Publication statusPublished - 2009
Externally publishedYes


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