Claudia Rodriguez

Publications (3)17.45 Total impact

• Article: Ubiquinone and menaquinone electron-carriers represent the Ying and Yang in the redox regulation of the ArcB sensor kinase.

  Adrián F Alvarez, Claudia Rodriguez, Dimitris Georgellis
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  ABSTRACT: The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to respiratory growth conditions. Under aerobic growth conditions, the ubiquinone electron carriers were proposed to silence the kinase activity of ArcB by oxidizing two cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond formation. Here, we confirm the role of the ubiquinone electron carriers as the silencing signal of ArcB in vivo, we show that the redox potential of ArcB is about -41 mV, and we demonstrate that the menaquinols are required for proper ArcB activation upon a shift from aerobic to anaerobic growth conditions. Thus, an essential link in the Arc signal transduction pathway connecting the redox-state of the quinone pool to the transcriptional apparatus is elucidated.
  Journal of bacteriology 05/2013; · 3.94 Impact Factor
• Source

  Available from: Dimitris Georgellis

  Article: Identification of a quinone-sensitive redox switch in the ArcB sensor kinase.

  Roxana Malpica, Bernardo Franco, Claudia Rodriguez, Ohsuk Kwon, Dimitris Georgellis
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  ABSTRACT: Escherichia coli senses and signals anoxic or low redox conditions in its growth environment by the Arc two-component system. Under anaerobic conditions, the ArcB sensor kinase autophosphorylates and transphosphorylates ArcA, a global transcriptional regulator that controls the expression of numerous operons involved in respiratory or fermentative metabolism. Under aerobic conditions, the kinase activity of ArcB is inhibited by the quinone electron carriers that act as direct negative signals. Here, we show that the molecular mechanism of kinase silencing involves the oxidation of two cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond formation, a reaction in which the quinones provide the source of oxidative power. Thus, a pivotal link in the Arc signal transduction pathway connecting the redox state of the quinone pool to the transcriptional apparatus is elucidated.
  Proceedings of the National Academy of Sciences 10/2004; 101(36):13318-23. · 9.68 Impact Factor
• Source

  Available from: Dimitris Georgellis

  Article: Effect of D-lactate on the physiological activity of the ArcB sensor kinase in Escherichia coli.

  Claudia Rodriguez, Ohsuk Kwon, Dimitris Georgellis
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  ABSTRACT: The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory growth conditions. Under anoxic growth conditions ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. The anaerobic metabolite D-lactate has been shown to stimulate the in vitro autophosphorylating activity of ArcB. In this study, the in vivo effect of D-lactate on the kinase activity of ArcB was assessed. The results demonstrate that D-lactate does not act as a direct signal for activation of ArcB, as previously proposed, but acts as a physiologically significant effector that amplifies ArcB kinase activity.
  Journal of Bacteriology 05/2004; 186(7):2085-90. · 3.83 Impact Factor