title: Trans-targeting of the phage Mu repressor is promoted by conformational changes that expose its ClpX recognition determinant.
abstract: Dominant negative forms of the phage Mu repressor, including the mutant Vir repressors, are not only rapidly degraded by the ClpXP protease but also promote degradation of the unmodified, wild-type repressor. This trans-targeting of the wild-type repressor depends upon a determinant within its C-terminal domain, which is needed for recognition by ClpX. An environmentally sensitive fluorescent probe (2-(4'-maleimidylanilino)naphthalene-6-sulfonic acid (MIANS)) attached to the C terminus of the full-length repressor indicated that Vir induces the movement of this domain into a more exposed configuration. Vir also promoted attachment of MIANS to the C terminus of the repressor at an accelerated rate, and it greatly increased the rate of phosphorylation of a cAMP-dependent protein kinase motif attached to the repressor C terminus. While an excess of Vir was needed to promote repressor phosphorylation at maximal rates, the presence of ClpX could increase phosphorylation rates at lower Vir levels. trans-Targeting of the Mu repressor is therefore promoted by exposing its ClpX recognition determinant, and the action of ClpX can assist Vir in exposing these determinants.
authors.affiliation: Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, DC 20057, USA.
authors.forename: Kimberly R
authors.initials: KR
authors.lastname: Marshall-Batty
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakai
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000817:Anilino Naphthalenesulfonates; D010583:Bacteriophage mu / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D017931:DNA Primers; D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D000817:Anilino Naphthalenesulfonates; D017931:DNA Primers; D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; D018832:Molecular Chaperones; D012097:Repressor Proteins; C021310:2-(4'-maleimidylanilino)naphthalene-6-sulfonic acid; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities