Abstract
The Arc two-component system modulates the expression of numerous genes in response to respiratory growth conditions. This system comprises ArcA as the response regulator and ArcB as the sensor kinase. ArcB is a tripartite histidine kinase whose activity is regulated by the oxidation of two cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond formation. Here, we report that the ArcB protein segment covering residues 70–121, fulfills the molecular characteristics of a leucine zipper containing coiled coil structure. Also, mutational analyses of this segment reveal three different phenotypical effects to be distributed along the coiled coil structure of ArcB, demonstrating that this motif is essential for proper ArcB signaling.
Highlights
The Arc two-component system plays an important role in the complex transcriptional regulatory network that allows facultative anaerobic bacteria, such as Escherichia coli, to sense changes in respiratory growth conditions and adapt their gene expression [1,2,3]
Leucine zippers are found in DNA-binding regulatory proteins [29], but are present in membrane proteins that do not bind to DNA [22,30,31,32,33]
Coiled coil motifs are often found in sensor kinases and in many cases they have been shown to play a significant role in the signaling mechanisms
Summary
The Arc (anoxic redox control) two-component system plays an important role in the complex transcriptional regulatory network that allows facultative anaerobic bacteria, such as Escherichia coli, to sense changes in respiratory growth conditions and adapt their gene expression [1,2,3]. This system consists of ArcB as the sensor kinase and ArcA as the response regulator [4,5]. Under nonstimulating conditions ArcB acts as a phosphatase that catalyzes the dephosphorylation of ArcA-P by a reverse Asp R His717 R Asp576 R Pi phosphorelay [7,18]
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