Transition metal ions are essential micronutrient for living organisms, being fundamental cofactors of many enzymes that catalyze an enormous variety of biological reactions. At the same time, several metal ions are toxic in their free form for cellular life, demanding a tight regulation of their intracellular trafficking and homeostasis. A paradigmatic example is represented by the human pathogen Helicobacter pylori, which relies on the activity of the nickel-dependent enzymes urease and hydrogenase to survive in the acidic stomach mucosa, where it is responsible of several diseases, such as gastric ulcer and cancer. In this bacterium, homeostasis of essential Ni2+ ions should be tightly controlled to allow growth and colonization. In this processes, NikR, a widespread homo-tetrameric transcription factor controlling the expression of proteins involved in nickel trafficking and/or nickel enzymes, plays a crucial role. The present study investigates the modulation of the interaction between Helicobacter pylori NikR (HpNikR) and DNA, exerted by different concentrations of Ni2+ and/or other metal ions. In particular, the thermodynamic parameters of the interaction between Ni2+, or other divalent metal ions, and HpNikR are determined by using isothermal titration calorimetry (ITC). The metal-dependent capability of HpNikR to bind PureA, the promoter of the urease operon, was determined by using mobility shift assays, DNAse footprinting and ITC. The results provide a congruent description of the factors that determine HpNikR binding to metal ions and DNA and yield clear proofs for activation of HpNikR selectively driven by Ni2+, through a protein conformational rearrangement specifically induced by Ni2+ binding (1-2). (1) B. Zambelli, M. Bellucci, A. Danielli, V. Scarlato, S. Ciurli; The Ni2+ binding properties of Helicobacter pylori NikR. Chem. Commun., 2007, 35, pp. 3649 - 3651 (2) B. Zambelli, A. Danielli, S. Romagnoli, P. Neyroz, S. Ciurli, V. Scarlato; High-affinity Ni2+ binding selectively promotes binding of Helicobacter pylori NikR to its target urease promoter. J. Mol. Biol., 2008, 383, pp. 1129 - 1143
Barbara Zambelli, Alberto Danielli, Vincenzo Scarlato, Stefano Ciurli (2010). Selectivity of Metal Ion Binding Specifically Drives the Interaction of a Ni2+-sensor with its operator DNA. BEIJING : s.n.
Selectivity of Metal Ion Binding Specifically Drives the Interaction of a Ni2+-sensor with its operator DNA
ZAMBELLI, BARBARA;DANIELLI, ALBERTO;SCARLATO, VINCENZO;CIURLI, STEFANO LUCIANO
2010
Abstract
Transition metal ions are essential micronutrient for living organisms, being fundamental cofactors of many enzymes that catalyze an enormous variety of biological reactions. At the same time, several metal ions are toxic in their free form for cellular life, demanding a tight regulation of their intracellular trafficking and homeostasis. A paradigmatic example is represented by the human pathogen Helicobacter pylori, which relies on the activity of the nickel-dependent enzymes urease and hydrogenase to survive in the acidic stomach mucosa, where it is responsible of several diseases, such as gastric ulcer and cancer. In this bacterium, homeostasis of essential Ni2+ ions should be tightly controlled to allow growth and colonization. In this processes, NikR, a widespread homo-tetrameric transcription factor controlling the expression of proteins involved in nickel trafficking and/or nickel enzymes, plays a crucial role. The present study investigates the modulation of the interaction between Helicobacter pylori NikR (HpNikR) and DNA, exerted by different concentrations of Ni2+ and/or other metal ions. In particular, the thermodynamic parameters of the interaction between Ni2+, or other divalent metal ions, and HpNikR are determined by using isothermal titration calorimetry (ITC). The metal-dependent capability of HpNikR to bind PureA, the promoter of the urease operon, was determined by using mobility shift assays, DNAse footprinting and ITC. The results provide a congruent description of the factors that determine HpNikR binding to metal ions and DNA and yield clear proofs for activation of HpNikR selectively driven by Ni2+, through a protein conformational rearrangement specifically induced by Ni2+ binding (1-2). (1) B. Zambelli, M. Bellucci, A. Danielli, V. Scarlato, S. Ciurli; The Ni2+ binding properties of Helicobacter pylori NikR. Chem. Commun., 2007, 35, pp. 3649 - 3651 (2) B. Zambelli, A. Danielli, S. Romagnoli, P. Neyroz, S. Ciurli, V. Scarlato; High-affinity Ni2+ binding selectively promotes binding of Helicobacter pylori NikR to its target urease promoter. J. Mol. Biol., 2008, 383, pp. 1129 - 1143I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
