Pressure-induced dissociation of tight couple ribosomes.
Ribosomes from Escherichia coli have been shown to undergo subunit dissociation at elevated hydrostatic pressure. This holds for both crude and highly purified ribosomes. No inhibitory effect could be detected by addition of either the S100 supernatant, or tRNA, polyuridylic acid, and spermine. Light scattering experiments at pressures up to 1000 bar reveal different susceptibility of tight couple and loose couple ribosomes toward pressure dissociation. Tight couples are subjected to EF-Tu-catalyzed binding of aminoacyl-tRNA, thus yielding a model system of the elongating ribosome before the peptidyl transfer step. High pressure dissociation of this compound suggests that enzymatic binding converts tight couples into loose couples. A hypothesis referring to conformational changes during the elongation cycle is presented.
Institut für Biophysik und Physikalische Biochemie, Universität Regensburg, FRG.
M
M
Gross
R
R
Jaenicke
D001665:Binding Sites; D002384:Catalysis; D004926:Escherichia coli / Q000254:growth & development* / Q000648:ultrastructure; D006874:Hydrostatic Pressure; D008027:Light; D008274:Magnesium / Q000494:pharmacology; D008954:Models, Biological; D010444:Peptide Elongation Factor Tu / Q000032:analysis / Q000502:physiology*; D011487:Protein Conformation; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012270:Ribosomes; D012542:Scattering, Radiation
D012346:RNA, Transfer, Amino Acyl; D010444:Peptide Elongation Factor Tu; D008274:Magnesium