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KMID : 0545120210310020233
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Journal of Microbiology and Biotechnology
2021 Volume.31 No. 2 p.233 ~ p.239
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Chromophorylation of a Novel Cyanobacteriochrome GAF Domain from Spirulina and Its Response to Copper Ions
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Jiang Su-Dan
Sheng Yi
Wu Xian-Jun
Zhu Yong-Li
Li Ping-Ping
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Abstract
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Cyanobacteriochromes (CBCRs) are phytochrome-related photoreceptor proteins in cyanobacteria and cover a wide spectral range from ultraviolet to far-red. A single GAF domain that they contain can bind bilin(s) autocatalytically via heterologous recombination and then fluoresce, with potential applications as biomarkers and biosensors. Here, we report that a novel red/green CBCR GAF domain, SPI1085g2 from Spirulina subsalsa, covalently binds both phycocyanobilin (PCB) and phycoerythrobilin (PEB). The PCB-binding GAF domain exhibited canonical red/green photoconversion with weak fluorescence emission. However, the PEB-binding GAF domain, SPI1085g2-PEB, exhibited an intense orange fluorescence (λabs.max = 520 nm, λfluor.max = 555 nm), with a fluorescence quantum yield close to 1.0. The fluorescence of SPI1085g2-PEB was selectively and instantaneously quenched by copper ions in a concentration-dependent manner and exhibited reversibility upon treatment with the metal chelator EDTA. This study identified a novel PEB-binding cyanobacteriochrome-based fluorescent protein with the highest quantum yield reported to date and suggests its potential as a biosensor for the rapid detection of copper ions.
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KEYWORD
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Cyanobacteriochrome, phycoerythrobilin, fluorescence quantum yield, biosensor, copper ions, fluorescence quenching
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