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PLoS One. 2015 Dec 23;10(12):e0145740. doi: 10.1371/journal.pone.0145740. eCollection 2015.

Crystal Structure of Phototoxic Orange Fluorescent Proteins with a Tryptophan-Based Chromophore.

Author information

1
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation.
2
Faculty of Biology, Moscow State University, Moscow, Russian Federation.
3
Nizhny Novgorod State Medical Academy, Nizhny Novgorod, Russian Federation.
4
Synchrotron Radiation Research Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Argonne, Illinois, United States of America.
5
Leidos Biomedical Research, Inc., Basic Research Program, Argonne, Illinois, United States of America.

Abstract

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 Å 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 β-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.

PMID:
26699366
PMCID:
PMC4689385
DOI:
10.1371/journal.pone.0145740
[Indexed for MEDLINE]
Free PMC Article

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