title: LonR9 carrying a single Glu614 to Lys mutation inhibits the ATP-dependent protease La (Lon) by forming mixed oligomeric complexes.
abstract: An unusual lon mutation (called lonR9) is dominant over the wild-type gene, which encodes the ATP-dependent protease La (Lon) in Escherichia coli, when present in multicopy plasmids. Here, we cloned and sequenced lonR9, and showed that the mutant gene carries a single point mutation in its open reading frame, which leads to replacement of Glu614 by Lys. The LonR9 protein and its poly-His-tagged form were purified to apparent homogeneity. Both of the purified proteins were capable of inhibiting the ATP-dependent proteolysis and the protein-activated ATP hydrolysis by protease La. Furthermore, the His-tagged LonR9 protein was found to form mixed oligomeric complexes with protease La, upon analysis by chromatography on a metal-chelating column. These results suggest that the phenotypic dominance of the lonR9 mutant is due to the formation of mixed oligomeric complexes between LonR9 and protease La, in which the defective components prevent the function of the wild-type subunits.
authors.affiliation: College of Natural Sciences, Seoul National University, Seoul, 151-742, Korea.
authors.forename: J Y
authors.initials: JY
authors.lastname: Oh
authors.forename: Y M
authors.initials: YM
authors.lastname: Eun
authors.forename: S J
authors.initials: SJ
authors.lastname: Yoo
authors.forename: J H
authors.initials: JH
authors.lastname: Seol
authors.forename: I S
authors.initials: IS
authors.lastname: Seong
authors.forename: C S
authors.initials: CS
authors.lastname: Lee
authors.forename: C H
authors.initials: CH
authors.lastname: Chung
mesh_terms: D049069:ATP-Dependent Proteases; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D001704:Biopolymers; D003001:Cloning, Molecular; D017931:DNA Primers; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010641:Phenotype; D049070:Protease La; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology
chemical_list: D001704:Biopolymers; D017931:DNA Primers; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D015842:Serine Proteinase Inhibitors; D006639:Histidine; D000255:Adenosine Triphosphate; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La