title: Delta Lys120, a mutation which destabilizes the ribosome-binding domain of ribosomal protein L7/L12.
abstract: Five-residue-long deletions centered on Ala63, Ala75, and Glu118 of ribosomal protein L7/L12 gave low mutant yields (5% or less) when the mutant genes were cloned in phage M13mp18 and controlled by the L10 promotor. Deletions of Glu118-Lys120 or Lys120 (the COOH-terminus of L7/L12) gave higher mutant yields, up to 50% with L7/L12 delta Lys120. L7/L12 delta Lys120 was not preferentially found in the S100 and not preferentially removed by LiCl washing, but was preferentially extracted from 70S ribosomes in the presence of 28-35% ethanol in 0.25-0.5 M NH4Cl. It follows that delta Lys120 destabilizes the ribosome-binding domain of ribosomal protein L7/L12 in an ethanol-containing solvent, which raises the question whether Lys120 is part of the ribosome-binding domain of L7/L12 during some step of protein synthesis or whether it is essential to preserve the conformation of the physiological ribosome-binding domain under structurally stressful conditions.
authors.affiliation: Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montréal, Que., Canada.
authors.forename: M
authors.initials: M
authors.lastname: Laughrea
authors.forename: E
authors.initials: E
authors.lastname: Higgins
mesh_terms: D000595:Amino Acid Sequence; D000643:Ammonium Chloride; D001483:Base Sequence; D001665:Binding Sites; D002499:Centrifugation, Density Gradient; D002712:Chlorides; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004586:Electrophoresis; D004926:Escherichia coli / Q000032:analysis / Q000648:ultrastructure; D000431:Ethanol; D008094:Lithium; D018021:Lithium Chloride; D008239:Lysine; D008969:Molecular Sequence Data; D009154:Mutation; D012269:Ribosomal Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D002712:Chlorides; D012269:Ribosomal Proteins; D000643:Ammonium Chloride; D000431:Ethanol; C016700:ribosomal protein L7-L12; D008094:Lithium; D018021:Lithium Chloride; D008239:Lysine