POSTERS - BLAST X - University of Utah
POSTERS - BLAST X - University of Utah
POSTERS - BLAST X - University of Utah
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<strong>BLAST</strong> X Mon. Morning Session<br />
INTRAMOLECULAR AUTOPHOSPHORYLATION OF THE ESCHERICHIA COLI ArcB<br />
SENSOR KINASE<br />
Gabriela R. Peña-Sandoval, Luis A. Nuñez Oreza and Dimitris Georgellis<br />
Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional<br />
Autónoma de México, 04510 México City, México.<br />
The Arc two-component system is a complex signal transduction system that plays a key<br />
role in regulating energy metabolism at the level <strong>of</strong> transcription in bacteria. This system<br />
comprises the ArcB protein, a tripartite membrane-associated sensor kinase, and the ArcA<br />
protein, a typical response regulator. Under anoxic growth conditions, ArcB autophosphorylates<br />
and transphosphorylates ArcA, which in turn represses or activates the expression <strong>of</strong> its target<br />
operons. Under aerobic conditions, the kinase activity <strong>of</strong> ArcB is silenced by the oxidation <strong>of</strong> two<br />
cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond<br />
formation, a reaction in which the quinones provide the source <strong>of</strong> oxidative power.<br />
Here we present results demonstrating that the putative leucine-zipper near the second<br />
transmembrane segment <strong>of</strong> ArcB is functional and necessary for proper ArcB signaling.<br />
Moreover, we provide data demonstrating that in contrast to the proposed model <strong>of</strong><br />
intermolecular autophosphorylation, ArcB autophosphorylation is an intra-molecular reaction.<br />
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