title: Phosphorylation in halobacterial signal transduction.
abstract: Regulated phosphorylation of proteins has been shown to be a hallmark of signal transduction mechanisms in both Eubacteria and Eukarya. Here we demonstrate that phosphorylation and dephosphorylation are also the underlying mechanism of chemo- and phototactic signal transduction in Archaea, the third branch of the living world. Cloning and sequencing of the region upstream of the cheA gene, known to be required for chemo- and phototaxis in Halobacterium salinarium, has identified cheY and cheB analogs which appear to form part of an operon which also includes cheA and the following open reading frame of 585 nucleotides. The CheY and CheB proteins have 31.3 and 37.5% sequence identity compared with the known signal transduction proteins CheY and CheB from Escherichia coli, respectively. The biochemical activities of both CheA and CheY were investigated following their expression in E.coli, isolation and renaturation. Wild-type CheA could be phosphorylated in a time-dependent manner in the presence of [gamma-32P]ATP and Mg2+, whereas the mutant CheA(H44Q) remained unlabeled. Phosphorylated CheA was dephosphorylated rapidly by the addition of wild-type CheY. The mutant CheY(D53A) had no effect on phosphorylated CheA. The mechanism of chemo- and phototactic signal transduction in the Archaeon H.salinarium, therefore, is similar to the two-component signaling system known from chemotaxis in the eubacterium E.coli.
authors.affiliation: Max Planck Institute for Biochemistry, Martinsried, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Rudolph
authors.forename: N
authors.initials: N
authors.lastname: Tolliday
authors.forename: C
authors.initials: C
authors.lastname: Schmitt
authors.forename: S C
authors.initials: SC
authors.lastname: Schuster
authors.forename: D
authors.initials: D
authors.lastname: Oesterhelt
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002633:Chemotaxis; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D006217:Halobacterium / Q000235:genetics / Q000502:physiology*; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009876:Operon; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli; C069656:CheB protein, Bacteria; D011494:Protein Kinases; D000071677:Histidine Kinase; C000607608:cheA protein, E coli