title: Rate of translation and kinetics of processing of newly synthesized molecules of two major outer-membrane proteins, the OmpA and OmpF proteins, of Escherichia coli K12.
abstract: The rate of synthesis of the OmpA and OmpF proteins, two of the major outer membrane proteins of Escherichia coli K12, was determined. At 25 degrees C both proteins were translated at 6.5 amino acids/s, and the OmpF protein was translated at 15 amino acids/s at 37 degrees C. The former rate corresponded to a synthesis time of just over 50 s for both proteins, which is significantly faster than their reported rates of assembly into the outer membrane at 25 degrees C. The kinetics of processing of the pro-OmpF protein were also investigated in detail, and the pro-OmpF half-life estimated to be 3-5 s at 25 degrees C. However a fraction of the precursor was processed more slowly, which may explain the discrepancy between these data and our earlier published estimate of 30 s. Pro-OmpA protein was processed with similar kinetics. These results demonstrate that the rate-limiting step in the assembly of both proteins into the outer membrane is post-translational and follows the processing step.
mesh_terms: D000917:Antibody Formation; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000096:biosynthesis*; D011232:Chemical Precipitation; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D007120:Immunochemistry; D007700:Kinetics; D008565:Membrane Proteins / Q000096:biosynthesis*; D014176:Protein Biosynthesis; D013696:Temperature
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D008565:Membrane Proteins