Charged residues render pro-OmpA potential dependent for initiation of membrane translocation.
We have examined the effects of positively and negatively charged residues on the translocation of outer membrane protein A precursor (pro-OmpA) across the bacterial inner membrane. Pro-OmpA does not translocate across the membrane when 2 positively charged residues are inserted immediately after the leader peptide, whereas it does insert when 2 neutral or negatively charged residues are introduced. Using a cell-free translocation system, we show that the membrane potential stimulated the rate of initial insertion of pro-OmpA with negatively charged residues, inhibited pro-OmpA with positively charged residues, and had no effect on neutral pro-OmpA. Thus, acidic residues render pro-OmpA potential-dependent for loop formation, which then initiates the translocation process.
Geller
B
B
Department of Chemistry, Ohio State University, Columbus 43210.
Zhu
H Y
HY
Cheng
S
S
Kuhn
A
A
Dalbey
R E
RE
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009243:NAD / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; C057184:outer membrane protein A precursor (E coli); D009243:NAD