Journal of Industrial Microbiology & Biotechnology

, Volume 46, Issue 12, pp 1669–1683 | Cite as

Genetically encoded FRET-based optical sensor for Hg2+ detection and intracellular imaging in living cells

  • Neha Soleja
  • Mohamad Aman Jairajpuri
  • Aarfa Queen
  • Mohd. MohsinEmail author
Fermentation, Cell Culture and Bioengineering - Original Paper


Due to the potential toxicity of mercury, there is an immediate need to understand its uptake, transport and flux within living cells. Conventional techniques used to analyze Hg2+ are invasive, involve high cost and are less sensitive. In the present study, a highly efficient genetically encoded mercury FRET sensor (MerFS) was developed to measure the cellular dynamics of Hg2+ at trace level in real time. To construct MerFS, the periplasmic mercury-binding protein MerP was sandwiched between enhanced cyan fluorescent protein (ECFP) and venus. MerFS is pH stable, offers a measurable fluorescent signal and binds to Hg2+ with high sensitivity and selectivity. Mutant MerFS-51 binds with an apparent affinity (Kd) of 5.09 × 10−7 M, thus providing a detection range for Hg2+ quantification between 0.210 µM and 1.196 µM. Furthermore, MerFS-51 was targeted to Escherichia coli (E. coli), yeast and human embryonic kidney (HEK)-293T cells that allowed dynamic measurement of intracellular Hg2+ concentration with a highly responsive saturation curve, proving its potential application in cellular systems.


Mercury Fluorescent proteins Genetically encoded FRET Nanosensors 



The first author (NS) is thankful to University Grants Commission for Senior Research Fellowship. Financial Assistant in the form of research grant under nanobiotechnology scheme (No. BT/PR22248/NNT/28/1272/2017) from Department of Biotechnology, Govt. of India for conducting this research work is gratefully acknowledged.

Author contributions

NS and MM designed the study and prepared the original manuscript. NS and MM conducted all in vitro and cellular experiments and analyzed the data. NS and MM did the live cell imaging of yeast and HEK cells and analyzed the data. AQ performed the cytotoxicity test. NS, MM and MAJ revised the manuscript. All authors were engaged in commenting on the manuscript. All authors read and approved the final manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

10295_2019_2235_MOESM1_ESM.doc (632 kb)
Supplementary material 1 (DOC 631 kb)


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Copyright information

© Society for Industrial Microbiology and Biotechnology 2019

Authors and Affiliations

  • Neha Soleja
    • 1
  • Mohamad Aman Jairajpuri
    • 1
  • Aarfa Queen
    • 2
  • Mohd. Mohsin
    • 1
    Email author
  1. 1.Department of BiosciencesJamia Millia IslamiaNew DelhiIndia
  2. 2.Department of ChemistryJamia Millia IslamiaNew DelhiIndia

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