INVESTIGADORES
CHECA Susana Karina
congresos y reuniones científicas
Título:
Characterization of a CueR variant that responds to +1 and +2 heavy metal ions.
Autor/es:
LESCANO J; SONCINI FC; CHECA SK
Lugar:
Paraná, Entre Ríos
Reunión:
Congreso; Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2018
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.
Resumen:
Resistance to toxic heavy metals in bacteria is controlled bycytoplasmic metalloregulators of the MerR family. Thesetranscriptional activators bind metals ions with high affinity at thedimer interface, using residues from both monomers. According to thearray of available ligands at the metal-coordination environment, MerRsensors are group in three categories: the CueR-like Cu(I)/Ag(I)/Au(I)sensors, the archetypal MerR Hg(II) sensors and the ZntR-likeZn(II)/Pb(II)/Cd(II) sensors. CueR coordinates +1 ions using twoconserved cysteine residues (C112 and C120) from one monomer.MerR and ZntR-like sensors use, in addition, a third C residue from theother monomer to bind +2 ions that require a high number ofcoordination ligands. Interestingly, CueR and its orthologues have aconserved serine (S77) in place of the third cysteine, but its relevance isstill unknown. We previously shown that a Salmonella Typhimuriumstrain carrying a cueR-S77C mutant allele activates CueR-controlledgenes in response to Cu(I), Ag(I), Au(I), and also to Hg(II).Furthermore, this mutant sensor also responds to Pb(II), Cd(II) andCo(II) in a strain lacking the Zn(II)/Pb(II)/Cd(II) transporter ZntA.Here, we reproduced the S77C mutation in the Escherichia coli CueRortholog from which structural data is available. Using specific reportergenes, we validated the response of EC-CueR-S77C to +1 and +2 metalions. We also analyzed and compared the interaction of EC-CueR-S77Cand EC-CueR with Pb(II) or Co(II) by recording the UV−vis spectra. Ourresults contribute to understand the importance of S77 in CueR-likeproteins for the exclusion of +2 ions from the metal binding site.