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Efficient membrane assembly of the KcsA potassium channel in Escherichia coli requires the protonmotive force
Author(s) -
van Dalen Annemieke,
Schrempf Hildgund,
Killian J Antoinette,
de Kruijff Ben
Publication year - 2000
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1093/embo-reports/kvd067
Subject(s) - kcsa potassium channel , biophysics , chemistry , transmembrane protein , biogenesis , tetramer , escherichia coli , potassium channel , membrane protein , atp hydrolysis , membrane , membrane potential , biochemistry , ion channel , biology , enzyme , atpase , receptor , gene
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 protonmotive 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, Δψ, is the main determinant for this effect. These results demonstrate a new role of the pmf in membrane protein biogenesis.