Efficient membrane assembly of the KcsA potassium channel in Escherichia coli requires the protonmotive force.
Very little is known about the biogenesis and assembly of oligomeric membrane proteins. In this study, the biogenesis of KcsA, a prokaryotic homotetrameric potassium channel, is investigated. Using in vivo pulse-chase experiments, both the monomeric and tetrameric form could be identified. The conversion of monomers into a tetramer is found to be a highly efficient process that occurs in the Escherichia coli inner membrane. KcsA does not require ATP hydrolysis by SecA for insertion or tetramerization. The presence of the proton-motive force (pmf) is not necessary for transmembrane insertion of KcsA; however, the pmf proved to be essential for the efficiency of oligomerization. From in vivo and in vitro experiments it is concluded that the electrical component, deltapsi, is the main determinant for this effect. These results demonstrate a new role of the pmf in membrane protein biogenesis.
van Dalen
A
A
Department Biochemistry of Membranes, Centre for Biomembranes and Lipid Enzymology, Institute of Biomembranes, Utrecht University, The Netherlands. a.vandalen@chem.uu.nl
Schrempf
H
H
Killian
J A
JA
de Kruijff
B
B
D000255:Adenosine Triphosphate / Q000378:metabolism; D001386:Azides / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D001692:Biological Transport; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000502:physiology*; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000502:physiology*; D014176:Protein Biosynthesis; D018892:Proton-Motive Force / Q000502:physiology*; D014158:Transcription, Genetic; D014357:Trypsin / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
D001386:Azides; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D014475:Uncoupling Agents; C107790:prokaryotic potassium channel; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000255:Adenosine Triphosphate; D014357:Trypsin