Checa, Susana

Research Lines

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). 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 mercury, zinc, lead, cadmium or cobalt, among others. 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.

 

PhD Fellows

Julian I. Mendoza

Julian Lescano

 

Selected Publications

Collaborators

  • María N. Lisa, Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay.

Grants

  • 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”
  • 2016-2019. Universidad Nacional de Rosario. “Análisis molecular y funcional de la resistencia a cobre y su relevancia para la patogénesis de Salmonella enterica“.
Checa, Susana

Position: Investigador Independiente
Laboratory: Transducción de Señales en Bacterias Patógenas
Sede: CCT
Email: checa@ibr-conicet.gov.ar
Tel. Interno: 637