A Green Fluorescent Protein with Photoswitchable Emission from the Deep Sea
A Green Fluorescent Protein with Photoswitchable Emission from the Deep Sea Alexander Vogt1, Cecilia D’Angelo1, Franz Oswald2, Andrea Denzel1, Charles H. Mazel3, Mikhail V. Matz4, Sergey Ivanchenko5, G. Ulrich Nienhaus5,6,Jo¨ rg Wiedenmann1,7* 1 Institute of General Zoology and Endocrinology, University of Ulm, Ulm, Germany, 2 Department of Internal Medicine I, University of Ulm, Ulm, Germany, 3 NightSea, Andover, Massachusetts, United States of America, 4 Integrative Biology, University of Texas in Austin, Austin, Texas, United States of America, 5 Institute of Biophysics, University of Ulm, Ulm, Germany, 6 Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America, 7 National Oceanography Centre, University of Southampton, Southampton, United Kingdom Abstract A colorful variety of fluorescent proteins (FPs) from marine invertebrates are utilized as genetically encoded markers for live cell imaging. The increased demand for advanced imaging techniques drives a continuous search for FPs with new and improved properties. Many useful FPs have been isolated from species adapted to sun-flooded habitats such as tropical coral reefs. It has yet remained unknown if species expressing green fluorescent protein (GFP)-like proteins also exist in the darkness of the deep sea. Using a submarine-based and -operated fluorescence detection system in the Gulf of Mexico, we discovered ceriantharians emitting bright green fluorescence in depths between 500 and 600 m and identified a GFP, named cerFP505, with bright fluorescence emission peaking at 505 nm. Spectroscopic studies showed that ,15% of the protein bulk feature reversible ON/OFF photoswitching that can be induced by alternating irradiation with blue und near- UV light.
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