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Biochem Biophys Res Commun. 2003 Nov 21;311(3):696-701.

Photoaffinity labeling under non-energized conditions of a specific drug-binding site of the ABC multidrug transporter LmrA from Lactococcus lactis.

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Institute of Parasitology, McGill University, Macdonald Campus, Ste-Anne de Bellevue, Que, Canada.

Erratum in

  • Biochem Biophys Res Commun. 2004 Jul 16;320(1):286. Alqwai Omar [corrected to Alqawi Omar].


The Lactococcus lactis multidrug resistance ABC transporter protein LmrA has been shown to confer resistance to structurally and functionally diverse antibiotics and anti-cancer drugs. Using a previously characterized photoreactive drug analogue of Rhodamine 123 (iodo-aryl azido-Rhodamine 123 or IAARh123), direct and specific photoaffinity labeling of LmrA in enriched membrane vesicles could be achieved under non-energized conditions. This photoaffinity labeling of LmrA occurs at a physiologically relevant site as it was inhibited by molar excess of ethidium bromide>Rhodamine 6G>vinblastine>doxorubicin>MK571 (a quinoline-based drug) while colchicine had no effect. The MDR-reversing agents PSC 833 and cyclosporin A were similarly effective in inhibiting IAARh123 photolabeling of LmrA and P-glycoprotein. In-gel digestion with Staphyloccocus aureus V8 protease of IAARh123-photolabeled LmrA revealed several IAARh123 labeled polypeptides, in addition to a 6.8kDa polypeptide that comprises the last two transmembrane domains of LmrA.

[Indexed for MEDLINE]

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