Requirement of the Receiver and Phosphotransfer Domains of ArcB for Efficient Dephosphorylation of Phosphorylated ArcA In Vivo

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 conditions of growth. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. Under aerobic growth conditions, phosphorylated ArcA (ArcA-P) dephosphorylates and its transcriptional regulation is released. The dephosphorylation of ArcA-P has been shown to occur, at least in vitro, via an ArcA Asp54 -P 3 ArcB His717 -P 3 ArcB Asp576 -P 3 P i reverse phosphorelay. In this study, the physiological significance of this pathway was assessed. The results demonstrate that the receiver and phosphotransfer domains of the tripartite sensor kinase ArcB are necessary and sufficient for efficient ArcA-P dephosphorylation in vivo.

A two-component phosphotransfer network involving ArcB, ArcA, and RssB coordinates synthesis and proteolysis of σS (RpoS) in E. coli

“…This network probably contains additional components, as RssB can also be activated by acetyl phosphate in a physiologically relevant way (Bouché et al 1998; see also below). Phosphorylation of ArcA by acetyl phosphate can also occur, and in the absence of ArcB, is likely to become relevant for ArcA activity (Pena-Sandoval et al 2005). Both branches of this network cooperate to maintain Figure 6.…”

“…ArcA and RssB are phosphorylated and cooperate to keep S levels low by repressing rpoS transcription and stimulating S proteolysis, respectively. Accessory components are acetyl phosphate, which contributes to RssB and perhaps also to ArcA phosphorylation (Bouché et al 1998;Pena-Sandoval et al 2005), as well as cAMP-CRP, which in log-phase cells has an indirect inhibitory effect on rpoS transcription (Lange and Hengge-Aronis 1994;F. Mika and R. Hengge, in prep.).…”

Cytokinin Regulates Type-A Arabidopsis Response Regulator Activity and Protein Stability via Two-Component Phosphorelay

“…A recent study indicates that the cytokinin receptor AHK4 determines phosphate flux through the system by regulating a bidirectional phosphorelay to and from the AHPs (Mahonen et al, 2006b). A bidirectional phosphorelay is also used by the bacterial Arc two-component system to mediate signal decay: the phosphoryl group from the ArcB response regulator is transferred back to the receiver domain of the ArcA tripartite His kinase via its His transmitter domain (Georgellis et al, 1998;Pena-Sandoval et al, 2005). It is possible that type-A ARR function may act by a similar mechanism of reverse phosphotransfer from type-B ARRs to type-A ARRs via AHPs, because phosphotransfer from AHPs to both type-A and type-B ARRs has been demonstrated in vitro Imamura et al, 2001Imamura et al, , 2003 and, in the presence of cytokinins, type-A ARRs, type-B ARRs, and AHPs mostly localize to the same subcellular compartments (Hwang and Sheen, 2001;Imamura et al, 2001Imamura et al, , 2003Kiba et al, 2003).…”

The ArcB Sensor Kinase of Escherichia coli Autophosphorylates by an Intramolecular Reaction

“…Under aerobic growth conditions, the quinone electron carriers inhibit the kinase activity of ArcB (8) through the oxidation of two redox-active cysteine residues that participate in intermolecular disulfide bond formation (24). Under such conditions, ArcB catalyzes the dephosphorylation of ArcA-P via an Asp 54 3 His 717 3 Asp 576 3 P i reverse phosphorelay (6,28). It has been previously reported that histidine kinases act as homodimers (4,33,35,36) and that they autophosphorylate by an intermolecular reaction (32).…”