PMC

Kinetics of 70S ribosome formation in the absence of IF1, IF3, tRNA and mRNA after rapid mixing of 50S subunits with 30S subunits containing different IF2s. (A) 30S subunits contained only indicated IF2. (B) Comparison of effective docking rates of 50S subunits to 30S subunits containing only IF2s or IF2s supplemented with also IF1 and mRNA.

Kinetics of 70S IC formation after rapid mixing of 50S subunits with 30S PICs containing different IF2s and either fMet-tRNA_i or no tRNA. (A) 30S PIC contained mRNA, IF1, no IF3, indicated IF2 and fMet-tRNA_i. (B) The same as (A) but fMet-tRNA_i was omitted. (C) 30S PICs contained mRNA, IF1, no IF3, indicated A-type IF2 mutants and either fMet-tRNA_i or no tRNA. (D) Effective docking rates of subunits with or without fMet-tRNA_i for indicated IF2s in the 30S PICs.

Dependence of the kinetics of subunit joining on the fraction of GTP in the reaction mixture for wild-type IF2 and A1 IF2 mutant. (A) Kinetics of 50S docking to 30S PICs containing mRNA, IF1, no IF3, fMet-tRNA_i and wild-type IF2 for indicated GTP fractions in the reaction mixture. (B) The same as (A) but 30S PICs contained A1 IF2 instead of wild-type IF2. (C) Comparison of the effective rates of subunit joining with wild-type IF2 and A1 IF2 mutant for different GTP fractions [GTP]/([GTP]+[GDP]) in the reaction mixture.

Kinetics of 70S IC formation after rapid mixing of 50S subunits with 30S PICs containing different IF2s and either non-formylated Met-tRNA_i or deacylated tRNA_i. (A) 30S PICs contained mRNA, IF1, no IF3, indicated IF2 and Met-tRNA_i. (B) Effective rates of subunit joining for the experiments in panel (A). (C) 30S PICs contained mRNA, IF1, no IF3, indicated IF2s and deacylated tRNA_i. (D) Comparison of effective docking rates of 50S subunits to 30S PICs assembled with indicated IF2s for different tRNA_i types (fMet-tRNA_i, Met-tRNA_i, deacylated tRNA_i or no tRNA).

Dependence of the kinetics of subunit joining on the presence of fMet-tRNA_i and G-nucleotide in the 30S PICs containing wild-type IF2 or A1 IF2 mutant. (A) Kinetics of 50S docking to 30S PICs containing mRNA, IF1, no IF3, wild-type IF2, indicated nucleotide and either fMet-tRNA_i or no tRNA. (B) The same as (A) but the 30S PICs contained A1 IF2 instead of wild-type IF2. (C) Comparison of the effective rates of 50S subunit docking to 30S PICs containing different G-nucleotides, fMet-tRNA_i or no tRNA and wild-type IF2 or A1 IF2 mutant.

Dependence of subunit-joining rate with wild-type IF2 and A1 IF2 mutant in the presence of IF3 on the fraction of GTP in the reaction mixture. (A) Kinetics of 50S docking to 30S PICs containing mRNA, IF1, IF3, fMet-tRNA_i and wild-type IF2 for indicated GTP fractions in the reaction mixture. (B) The same as (A) but 30S PICs contained A1 IF2 instead of wild-type IF2. (C) Comparison of the effective rates of subunit joining with wild-type IF2 and A1 IF2 mutant for different GTP fractions [GTP]/([GTP]+[GDP]) in the reaction mixture.