A new bivalent fluorescent fusion protein for differential Cu(II) and Zn(II) ion detection in aqueous solution

Simple and easy to engineer metal-sensing molecules that are capable of differentiating metal ions and producing metal-specific signals are highly desirable. Metal ions affect the thermal stability of proteins by increasing or decreasing their resistance to unfolding. This work illustrates a new str...

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Bibliographic Details
Published in:Analytica chimica acta 2020-03, Vol.1101, p.120-128
Main Authors: Sorenson, A.E., Schaeffer, P.M.
Format: Article
Language:English
Subjects:
Biosensor
Biotin protein ligase
Burkholderia
Chemodosimeter
Copper
Dengue RNA-Dependent-RNA-Polymerase
Differential scanning fluorimetry
DNA ligase
DnaG primase
DSF-GTP
Green fluorescent protein
HIV integrase
Mycobacterium
Zinc
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Summary:Simple and easy to engineer metal-sensing molecules that are capable of differentiating metal ions and producing metal-specific signals are highly desirable. Metal ions affect the thermal stability of proteins by increasing or decreasing their resistance to unfolding. This work illustrates a new strategy for designing bivalent fluorescent fusion proteins capable of differentiating metal ions in solution through their distinct effects on a protein’s thermal stability. A new dual purpose metal sensor was developed consisting of biotin protein ligase (BirA) from B. pseudomallei (Bp) fused to green fluorescent protein (GFP). When coupled with differential scanning fluorimetry of GFP-tagged proteins (DSF-GTP) for signal-transduction detection, Bp BirA-GFP yields distinct protein unfolding signatures with Zn(II) and Cu(II) ions in aqueous solutions. The limit of detection of the system is ∼1 μM for both metal species. The system can be used in a variety of high-throughput assay formats including for the screening of metal-binding proteins and chelators. Bp BirA-GFP has also the additional benefit of being useful in Cu(II) ion field-testing applications through simple visual observation of a temperature-dependent loss of fluorescence. Bp BirA-GFP is the first example of a protein-based dual purpose Cu(II) and Zn(II) ion sensor compatible with two different yet complementary signal-transduction detection systems. [Display omitted] •Burkholderia pseudomallei biotin protein ligase senses copper and zinc ions in water.•GFP-tagged biotin protein ligase differentiates between copper and zinc ions.•The assay format allows high-throughput screening of metal chelating agents.•A simple visual in-field water testing format was devised for copper ion detection.•Recommended maximum impurity concentrations of copper are easily detected in water.
ISSN:0003-2670
1873-4324
DOI:10.1016/j.aca.2019.12.017