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Publication Abstract from PubMed

Phototoxic fluorescent proteins represent a sparse group of genetically encoded photosensitizers that could be used for precise light-induced inactivation of target proteins, DNA damage, and cell killing. Only two such GFP-based fluorescent proteins (FPs), KillerRed and its monomeric variant SuperNova, were described up to date. Here, we present a crystallographic study of their two orange successors, dimeric KillerOrange and monomeric mKillerOrange, at 1.81 and 1.57 A resolution, respectively. They are the first orange-emitting protein photosensitizers with a tryptophan-based chromophore (Gln65-Trp66-Gly67). Same as their red progenitors, both orange photosensitizers have a water-filled channel connecting the chromophore to the beta-barrel exterior and enabling transport of ROS. In both proteins, Trp66 of the chromophore adopts an unusual trans-cis conformation stabilized by H-bond with the nearby Gln159. This trans-cis conformation along with the water channel was shown to be a key structural feature providing bright orange emission and phototoxicity of both examined orange photosensitizers.

Crystal Structure of Phototoxic Orange Fluorescent Proteins with a Tryptophan-Based Chromophore.,Pletneva NV, Pletnev VZ, Sarkisyan KS, Gorbachev DA, Egorov ES, Mishin AS, Lukyanov KA, Dauter Z, Pletnev S PLoS One. 2015 Dec 23;10(12):e0145740. doi: 10.1371/journal.pone.0145740., eCollection 2015. PMID:26699366^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.