title: Protons and Mg2+ cations as probes in investigating the role of GTP in initiation complex formation.
abstract: fMet-tRNAfMet binding to both 30-S subunits and to 70-S particles is dependent on both pH AND Mg2+ concentration: for fMet-tRNAfMet binding to 70-S particles, variations of pH and Mg2+ concentration are tightly interdependent. This behavior can be interpreted by the polyelectrolyte theory as a direct consequence of the fact that the binding occurs in a polyanionic micro-environment. The pH-dependent binding to 70-S particles clearly shows the involvement of two prototropic groups which appear to be those carrying out GTP hydrolysis, therefore directly linked to initiation complex formation; in the presence of a non-hydrolyzable analogue to GTP, guanosine 5'-[beta, gamma-imido]triphosphate, the binding of fMet-tRNAfMet shows much less interdependence between variation of pH and Mg2+ concentration.
mesh_terms: D001665:Binding Sites; D004926:Escherichia coli / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008970:Molecular Weight; D009239:N-Formylmethionine / Q000378:metabolism; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism
chemical_list: D010448:Peptide Initiation Factors; D012346:RNA, Transfer, Amino Acyl; D006165:Guanylyl Imidodiphosphate; D009239:N-Formylmethionine; D006160:Guanosine Triphosphate; D008274:Magnesium