title: FixK₂, a key regulator in Bradyrhizobium japonicum, is a substrate for the protease ClpAP in vitro.
abstract: FixK₂ is a CRP-like transcription factor that controls the endosymbiotic lifestyle of Bradyrhizobium japonicum. The reason for its noticeable protease sensitivity was explored here. The repertoire of Clp chaperone-proteases in B. japonicum was examined, and specifically ClpAP₁ and ClpXP₁ were purified and tested. FixK₂ was found to be degraded by ClpAP₁ but not by ClpXP₁. Degradation was inhibited by the ClpS₁ adaptor protein, indicating that FixK₂ is a direct substrate for ClpAP₁. The last 12 amino acids of FixK₂ appeared to be recognized by ClpA. The results suggest that the ClpAP system is involved in the cellular turnover of FixK₂.
authors.affiliation: ETH Zurich, Institute of Microbiology, Wolfgang-Pauli-Str. 10, CH-8093 Zürich, Switzerland. bonnetmariette@yahoo.fr
authors.forename: Mariette
authors.initials: M
authors.lastname: Bonnet
authors.forename: Monika
authors.initials: M
authors.lastname: Stegmann
authors.forename: Željka
authors.initials: Ž
authors.lastname: Maglica
authors.forename: Emanuel
authors.initials: E
authors.lastname: Stiegeler
authors.forename: Eilika
authors.initials: E
authors.lastname: Weber-Ban
authors.forename: Hauke
authors.initials: H
authors.lastname: Hennecke
authors.forename: Socorro
authors.initials: S
authors.lastname: Mesa
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001665:Binding Sites; D020369:Bradyrhizobium / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D049071:Endopeptidase Clp / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005798:Genes, Bacterial; D007527:Isoenzymes / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D018832:Molecular Chaperones / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D054730:Protein Interaction Domains and Motifs; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D007527:Isoenzymes; D018832:Molecular Chaperones; D020033:Protein Isoforms; D011994:Recombinant Proteins; C066628:FixK protein, Bacteria; D049071:Endopeptidase Clp