title: The ribosomal binding domain of the Escherichia coli release factors. Modification of tyrosine in the N-terminal domain of ribosomal protein L11 affects release factors 1 and 2 differentially.
abstract: Ribosomal protein L11 is one of only two ribosomal proteins significantly iodinated when Escherichia coli 50 S subunits are modified by immobilized lactoperoxidase, and the major target has been shown previously to be tyrosine at position 7 in the N-terminal domain. This modification reduces in vitro termination activity with release factor (RF)-1 by 70-90%, but RF-2 activity is less affected (30-50%). The loss of activity parallels incorporation of iodine into the subunit. The 50 S subunits from L11-lacking strains of bacteria have highly elevated activity with RF-2 and low activity with RF-1. The iodination does not affect RF-2 activity but reduces the RF-1 activity further. Ribosomal proteins, L2, L6, and L25, are significantly labeled in L11-lacking ribosomes in contrast to the control 50 S subunits. L11 has been modified in isolation and incorporated back efficiently into L11-lacking ribosomes. This L11, iodinated also predominantly at Tyr 7, is unable to restore RF-1 activity to L11-lacking ribosomes in contrast to mock-iodinated protein. These results suggest the involvement of the N terminus of L11 in the binding domain of the bacterial release factors and indicate that there are subtle differences in how the two factors interact with the ribosome.
mesh_terms: D001665:Binding Sites; D004926:Escherichia coli / Q000378:metabolism*; D010443:Peptide Chain Termination, Translational; D010454:Peptide Termination Factors / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
chemical_list: D010454:Peptide Termination Factors; D012269:Ribosomal Proteins; C041460:peptide chain termination release factor 2; C027624:ribosomal protein L11; D014443:Tyrosine