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A blue fluorescent protein from a yellow-emitting luminous bacterium
H Karatani1, T Wilson, J W Hastings
1Department of Cellular and Developmental Biology, Harvard University, Cambridge, MA 02138.
Photochemistry and Photobiology
|February 1, 1992
Summary
Vibrio fischeri strain Y1 produces a novel blue fluorescent protein (Y1-BFP) alongside yellow fluorescent protein (YFP). Y1-BFP modulates luciferase activity differently than YFP, impacting light emission intensity and kinetics.
Area of Science:
- Bioluminescence
- Fluorescent Proteins
- Bacterial Physiology
Background:
- Vibrio fischeri strain Y1 emits yellow light in vivo, attributed to yellow fluorescent protein (YFP) in its luciferase system.
- The presence of other fluorescent proteins in bioluminescent bacteria is plausible and warrants investigation.
Purpose of the Study:
- To characterize a newly identified blue fluorescent protein (Y1-BFP) from Vibrio fischeri strain Y1.
- To investigate the biochemical interactions of Y1-BFP with homologous and heterologous luciferase systems.
Main Methods:
- Purification of Y1-BFP.
- Spectroscopic analysis (excitation, emission, fluorescence lifetime, molar extinction coefficient).
- In vitro assays with purified Y1-BFP and luciferase from Vibrio fischeri and Vibrio harveyi.
Main Results:
- Y1-BFP, with a molecular weight of ~25 kDa, exhibits fluorescence excitation/emission maxima at 416/461 nm and a fluorescence lifetime of 12.5 ns at 2°C.
- Y1-BFP reduces light intensity and decay rate with homologous luciferase but does not alter the emission spectrum.
- Y1-BFP causes a minor blue-shift (~10 nm) in the emission spectrum when used with Vibrio harveyi luciferase.
Conclusions:
- Vibrio fischeri strain Y1 possesses both YFP and Y1-BFP, contributing to its complex light emission properties.
- Y1-BFP interacts with luciferase, modulating reaction kinetics and emission spectra depending on the luciferase source, distinct from YFP's effects.