Phosphatidylglycerol dependent protein translocation across the Escherichia coli inner membrane is inhibited by the anti-cancer drug doxorubicin. Evidence for an electrostatic interaction between the signal sequence and phosphatidylglycerol.
OmpF-Lpp, a model secretory protein, requires both a positively charged signal sequence and phosphatidylglycerol (PG) for efficient translocation across the E. coli inner membrane. Modification of the signal sequence can, however, remove both these prerequisites for translocation providing OmpF-Lpp mutants which undergo either PG and charge dependent or PG and charge independent translocation. Here we show that positively charged membrane interactive compounds (polylysine & doxorubicin) are able to inhibit PG dependent translocation of the OmpF-Lpp signal sequence mutants but not PG independent translocation. Doxorubicin is also shown to bind more efficiently to liposomes containing increased levels of anionic lipid indicating that in these assays it may be inhibiting translocation by preventing electrostatic interaction between the anionic lipid head group and the positively charged signal sequences.
Centre for Biomembranes and Lipid Enzymology, University of Utrecht, The Netherlands.
D A
DA
Phoenix
F A
FA
de Wolf
Rutger
W H
WH
Staffhorst
C
C
Hikita
S
S
Mizushima
B
B
de Kruijff
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004317:Doxorubicin / Q000378:metabolism / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism*; D010715:Phosphatidylglycerols / Q000378:metabolism*; D014176:Protein Biosynthesis; D021382:Protein Sorting Signals / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D014158:Transcription, Genetic
D001425:Bacterial Outer Membrane Proteins; D008074:Lipoproteins; C066293:OmpF-Lpp chimeric protein; D010715:Phosphatidylglycerols; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D004317:Doxorubicin