ProOmpA is stabilized for membrane translocation by either purified E. coli trigger factor or canine signal recognition particle.
We have isolated large amounts of E. coli outer-membrane protein A precursor (proOmpA). Purified proOmpA is active in membrane assembly, and this assembly is saturable with respect to the precursor protein. A proOmpA-Sepharose matrix allows affinity isolation of trigger factor, a soluble, 63,000 dalton monomeric protein that stabilizes proOmpA in assembly competent form. Comparison of trigger factor's amino-terminal sequence with those in a computer data bank and with those encoded by sec genes, as well as groEL and heat shock gene dnaK, suggests that trigger factor is encoded by a previously undescribed gene. Trigger factor and proOmpA form a 1:1 complex that can be isolated by gel filtration. Purified canine signal recognition particle (SRP) can also stabilize proOmpA for membrane insertion. This postribosomal activity of SRP suggests a unifying theme in protein translocation mechanisms.
Crooke
E
E
Molecular Biology Institute, University of California, Los Angeles 90024-1570.
Guthrie
B
B
Lecker
S
S
Lill
R
R
Wickner
W
W
D000591:Amino Acid Isomerases / Q000302:isolation & purification / Q000502:physiology*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000502:physiology*; D001692:Biological Transport; D002352:Carrier Proteins / Q000302:isolation & purification / Q000502:physiology*; D002853:Chromatography, Liquid; D004285:Dogs; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008566:Membranes / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D010179:Pancreas / Q000378:metabolism; D019696:Peptidylprolyl Isomerase; D011485:Protein Binding; D011498:Protein Precursors / Q000302:isolation & purification / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000494:pharmacology*; D018271:Signal Recognition Particle
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D011498:Protein Precursors; D012261:Ribonucleoproteins; D018271:Signal Recognition Particle; C057184:outer membrane protein A precursor (E coli); D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase