The efflux of a fluorescent probe is catalyzed by an ATP-driven extrusion system in Lactococcus lactis.

AUTOR(ES)

Molenaar, D

RESUMO

Many bacteria, both gram positive and gram negative, extrude in an energy-dependent manner the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5[and -6]-carboxyfluorescein (BCECF) (D. Molenaar, T. Abee, and W. N. Konings, Biochim. Biophys. Acta 1115:75-83, 1991). This efflux was studied in detail in Lactococcus lactis, and several indications that a transport system is involved were found. This transport system is most likely driven by ATP or a related compound. The evidence is that BCECF extrusion (i) occurs against a BCECF gradient, (ii) is strictly correlated with ATP concentration and not with the proton motive force, and (iii) is inhibited by vanadate and to a lesser extent by N,N'-dicyclohexylcarbodiimide. Most convincingly, a UV mutant with a strongly reduced efflux rate was isolated. Such a mutant was isolated from a BCECF-loaded and lactose-energized population by selection of highly fluorescent cells in a flow cytometer-cell sorter. The physiological function of this extrusion system is unknown, but its characteristics classify it among the traffic ATPases.

Documentos Relacionados

• Proton motive force-driven and ATP-dependent drug extrusion systems in multidrug-resistant Lactococcus lactis.
• Identification of the structural proteins of an ATP-driven potassium transport system in Escherichia coli.
• Mechanism of ATP-driven electron transfer catalyzed by the benzene ring-reducing enzyme benzoyl- CoA reductase
• ATP-driven sodium pump in Streptococcus faecalis.
• ATP-driven stepwise rotation of FoF1-ATP synthase