title: A point mutation within the ATP-binding site inactivates both catalytic functions of the ATP-dependent protease La (Lon) from Escherichia coli.
abstract: A point mutant in the ATP-binding motif (GPPGVGK362T) of the ATP-dependent protease La from Escherichia coli was investigated in which the lysine at position 362 was replaced by an alanine. The catalytic efficiency of the K362A mutant is at least two orders of magnitude lower than that of wild-type protease La due to a decreased Vmax and an increased KM for ATP. Simultaneously, the peptidase activity of La K362A is almost completely eliminated. Since selective inactivation of the peptidase activity of La does not affect its intrinsic ATPase activity, coupling of proteolysis with ATP hydrolysis is only uni-directional in this energy-dependent protease.
authors.affiliation: Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Hönggerberg, Zürich, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Fischer
authors.forename: R
authors.initials: R
authors.lastname: Glockshuber
mesh_terms: D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000409:Alanine / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002384:Catalysis; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D017354:Point Mutation; D049070:Protease La; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D009838:Oligodeoxyribonucleotides; D000255:Adenosine Triphosphate; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La; D000251:Adenosine Triphosphatases; D008239:Lysine; D000409:Alanine