Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Record number 418513
Title Green-Fluorescent Protein from the Bioluminescent Jellyfish Clytia gregaria Is an Obligate Dimer and Does Not Form a Stable Complex with the Ca2+-Discharged Photoprotein Clytin.
Author(s) Malikova, N.P.; Visser, N.V.; Hoek, A. van; Skakun, V.V.; Vysotski, E.S.; Lee, J.; Visser, A.J.W.G.
Source Biochemistry 50 (2011)20. - ISSN 0006-2960 - p. 4232 - 4241.
DOI http://dx.doi.org/10.1021/bi101671p
Department(s) Biophysics
Biochemistry
EPS
Publication type Refereed Article in a scientific journal
Publication year 2011
Keyword(s) vibrio-fischeri y1 - energy-transfer - correlation spectroscopy - bacterial luciferase - refractive-index - photobacterium-leiognathi - polarized fluorescence - excitation transfer - recombinant obelin - lumazine protein
Abstract Green-fluorescent protein (GFP) is the origin of the green bioluminescence color exhibited by several marine hydrozoans and anthozoans. The mechanism is believed to be Fo¨rster resonance energy transfer (FRET) within a luciferase-GFP or photoprotein-GFP complex. As the effect is found in vitro at micromolar concentrations, for FRET to occur this complex must have an affinity in the micromolar range. We present here a fluorescence dynamics investigation of the recombinant bioluminescence proteins from the jellyfish Clytia gregaria, the photoprotein clytin in its Ca2+-discharged form that is highly fluorescent (¿max = 506 nm) and its GFP (cgreGFP; ¿max = 500 nm). Ca2+-discharged clytin shows a predominant fluorescence lifetime of 5.7 ns, which is assigned to the final emitting state of the bioluminescence reaction product, coelenteramide anion, and a fluorescence anisotropy decay or rotational correlation time of 12 ns (20 °C), consistent with tight binding and rotation with the whole protein. A 34 ns correlation time combined with a translational diffusion constant and molecular brightness from fluorescence fluctuation spectroscopy all confirm that cgreGFP is an obligate dimer down to nanomolar concentrations. Within the dimer, the two chromophores have a coupled excited-state transition yielding fluorescence depolarization via FRET with a transfer correlation time of 0.5 ns. The 34 ns time of cgreGFP showed no change upon addition of a 1000-fold excess of Ca2+-discharged clytin, indicating no stable complexation below 0.2 mM. It is proposed that any bioluminescence FRET complex with micromolar affinity must be one formed transiently by the cgreGFP dimer with a short-lived (millisecond) intermediate in the clytin reaction pathway.
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