Ion conductivity of the bacterial translocation channel SecYEG engaged in translocation
Sprache des Vortragstitels:
Englisch
Original Tagungtitel:
Gordon Research COnference: Protein Transport Across Cell Membranes
Sprache des Tagungstitel:
Englisch
Original Kurzfassung:
Ion conductivity of the bacterial translocation channel SecYEG engaged in translocation
Denis Knyazev, Christine Siligan, Lukas Winter, Peter Pohl
Johannes Kepler University, Linz, Austria
While engaged in protein transport, the bacterial translocon SecYEG must maintain the membrane barrier to small ions. The preservation of the proton motif force in in vivo and in vitro experiments with SecYEG mutants in the bacterial plasma membrane was partly attributed to cation exclusion by the channel. Here we show that the purified and reconstituted SecYEG facilitates both cation and anion transport. But when engaged in translocation, the channel closes its gate to small molecules at physiological values of the membrane potential. This is also true for both plug deletion and pore ring mutants with a stalled translocation intermediate. The remaining leak current shows little ion selectivity and is two orders of magnitude smaller than the current through the open SecYEG channel.
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