Phosphotransfer circuitry of the putative multi-signal transducer, ArcB, of Escherichia coli: in vitro studies with mutants.
Recently we demonstrated the occurrence of a novel device of signal transducers in Escherichia coli. This class of bacterial sensory kinases, typified by ArcB and BarA, possesses two phospho-donor (His) sites, together with a phospho-accepting (Asp) site. These multi-phosphorylation sites were suggested to make a phosphotransfer circuit. To clarify this complex circuitry, we carried out a series of in vitro assays involving a set of ArcB mutant proteins which have an amino acid substitution at each putative phosphorylation site (His-292, Asp-576 and His-717). By these in vitro phosphorylation and/or phosphotransfer assays, the followings were assessed: (i) ArcB autophosphorylation; (ii) ArcB-mediated phosphorylation of the cognate response regulator, ArcA; (iii) ArcB-mediated phosphorylation of its truncated form (ArcBc) encompassing only the C-terminal phosphorylation site (His-717); (iv) phosphotransfer from ArcBc to ArcA; and (v) phosphotransfer from ArcBc to ArcB. On the basis of these in vitro results, a complex circuitry was revealed for the signal transducer ArcB. This evidence obtained in vitro supports the view that ArcB can serve as a powerful device for not only propagating multi-signals, but also making up signalling networks, in ways more sophisticated than previously thought.
Tsuzuki
M
M
Laboratory of Molecular Microbiology, Nagoya University, Japan.
Ishige
K
K
Mizuno
T
T
D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D010766:Phosphorylation; D011494:Protein Kinases; D012097:Repressor Proteins; D015398:Signal Transduction
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D009838:Oligodeoxyribonucleotides; D012097:Repressor Proteins; C041610:arcA protein, E coli; D011494:Protein Kinases; C065271:arcB protein, E coli