Proton motive force involved in protein transport across the outer membrane of Aeromonas salmonicida

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Science  03 Nov 1989:
Vol. 246, Issue 4930, pp. 654-656
DOI: 10.1126/science.2814486


Many Gram-negative bacteria export proteins to the exterior. Some of these proteins are first secreted into the periplasm and then cross the outer membrane in a separate step. The source of energy required for the translocation is unknown. Export of the extracellular protein proaerolysin from the periplasm through the outer membrane of Aeromonas salmonicida is inhibited by a proton ionophore and by low extracellular pH. One possible explanation of these results is that a proton gradient across the outer membrane is required for export.

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