Structural and functional characterization of GolS and GolS-controlled transporters
The MerR family of metalloregulators activates the expression of specific metal resistance determinants in response to the presence of free metal ions at the bacterial cytoplasm. Most of these biological sensors are poorly selective and recognize more than one metal ion with similar size, charge or coordination chemistry. Basically MerR sensors can be divided in three groups according with the metal ion/s they detect: the monovalent metal ion sensors that respond to Cu(I), Ag(I) and/or Au(I), such as the non-selective Cu sensor CueR or the Au sensors GolS and CupR; the divalent metal sensors responding to Zn(II),Cd(II),Co(II) and/or Pb(II), such as the non-selective Zn sensor ZntR or the Pb sensor PbrR; and the archetypal Hg sensor MerR. In our laboratory, we are carrying out the functional and structural characterization of GolS, CueR and ZntR from Salmonella enterica in order to identify the molecular bases that direct the specific recognition of selective metal ions and the residues involved in allosteric transduction of the input signal to the DNA-binding domain to activate transcription. Also, we are investigating the role of the GolS-controlled factors, the envelope-associated transporters, GolT and GesABC, and the cytoplasmic metal-binding protein GolB, for preserving survival and allow adaptation in different environments.
Design of bacterial biosensor for detecting heavy metal
Bacterial biosensors are microorganisms that have been genetically modified to couple detection of a compound to production of an easily quantifiable reporter signal. The development of these devices for the detection of heavy metals has become particularly important in recent years because they are cheap to produce, but also, because it reports only the fraction of the metal that is bioavailable. In consequence, they are particularly useful for assessing environmental risk. In our laboratory we have developed the first fluorescent bacterial biosensor for the selective detection of soluble gold and other that simultaneously detects a wide range of metals, including mercury, lead and cadmium, metals highly dangerous to humans (Figure 1). Recently we construct a mercury-specific sensor based on a modified GolS sensor. In order to generate new and more efficient screening tools, we will perform directed evolution to the sensor protein in order to obtain bioreporters that selectively detect different toxic metals such as lead, cadmium, zinc or cobalt. We also plan to optimize immobilization procedures and preservation of bacteria bioreporters to enable the construction of measuring instruments or devices useful in the evaluation of drinking water or industrial effluents.
Julian I. Mendoza
- Mendoza JI, Soncini FC and Checa SK (2020) Engineering of a Au-sensor to develop a Hg-specific, sensitive and robust whole-cell biosensor for on-site monitoring. Chem. Comm. (in press) – https://pubs.rsc.org/en/content/articlelanding/2020/CC/D0CC01323D#!divAbstract
- Cerminati S, Giri GF, Mendoza JI, Soncini FC and Checa SK (2017) The CpxR/CpxA system contributes to Salmonella gold-resistance by controlling the GolS-dependent gesABC transcription. Env. Microbiol. 19(10):4035-4044. –http://onlinelibrary.wiley.com/doi/10.1111/1462-2920.13837/abstract;jsessionid=ED3232EF2F0AB19E533346641DE46C1B.f02t04
- Cerminati S, Soncini FC and Checa SK (2015) A sensitive whole-cell biosensor for the simultaneous detection of a broad-spectrum of toxic heavy metal ions. Chem. Comm. 51(27):5917-5920. –http://pubs.rsc.org/en/Content/ArticleLanding/2015/CC/C5CC00981B#!divAbstract
- Ibáñez MM, Checa SK* and Soncini FC* (2015) A single serine residue determines selectivity to monovalent metal ions in metalloregulators of the MerR family. J. Bacteriol. 197(9):1606 –1613. – http://jb.asm.org/content/197/9/1606.long
- Soncini FC and Checa SK (2014) Gold. In Binding, Transport and Storage of Metal Ions in Biological Cells. (Maret, W. and Wedd, A. G., eds.) The Royal Society of Chemistry, Cambridge, United Kingdom. – http://pubs.rsc.org/en/content/chapter/bk9781849735995-00582/978-1-84973-599-5
- Ibáñez MM, Cerminati S, Checa SK and Soncini FC (2013) Dissecting the metal-selectivity of MerR monovalent metal ion sensors in Salmonella. J. Bacteriol. 195(13):3084-92. – http://jb.asm.org/content/195/13/3084.long
- Checa SK*, Zurbriggen MD and Soncini FC (2012) Bacterial signaling systems as platforms for rational design of new generations of biosensors. Curr. Opin. Biotechnol. 23:766-772. – http://www.sciencedirect.com/science/article/pii/S0958166912000705?via%3Dihub
- Cerminati S, Soncini, FC and Checa SK (2011) Selective detection of gold using genetically engineered bacterial reporters. Biotechnol. Bioeng. 108, 2553-2560. – http://onlinelibrary.wiley.com/doi/10.1002/bit.23213/abstract
- María N. Lisa, Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay.
- José M. Argüello, Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, USA.
- PICT-2015-2339. Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT). “Generación de sensores biológicos sensibles y selectivos para evaluar contaminación de las aguas por metales pesados”
- BIO552 (2018-2022). Universidad Nacional de Rosario. “Caracterización molecular y biotecnología de metalo-sensores bacterianos”.
Position: Investigador Independiente
Laboratory: Transducción de Señales en Bacterias Patógenas
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