Structure and dynamics of the membrane-embedded domain of LmrA investigated by coupling polarized ATR-FTIR spectroscopy and H-1/H-2 exchange

[No Value] Grimard, C Vigano, A Margolles, R Wattiez, HW van Veen, WN Konings, JM Ruysschaert, E Goormaghtigh*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

35 Citations (Scopus)

Abstract

Bacterial LmrA, an integral membrane protein of Lactococcus lactis, confers multidrug resistance by mediating active extrusion of a wide variety of structurally unrelated compounds. Similar to its eucaryotic homologue P-gp, this protein is a member of the ATP-binding cassette (ABC) superfamily. Different predictive models, based on hydropathy profiles, have been proposed to describe the structure of the ABC transporters in general and of LmrA in particular. We used polarized attenuated total reflection infrared spectroscopy, combined with limited proteolysis, to investigate the secondary structure and the orientation of the transmembrane segments of LmrA. We bring the first experimental evidence that the membrane-embedded domain of LmrA is composed of transmembrane-oriented a-helices. Furthermore, a new approach was developed in order to provide information about membrane domain dynamics. Monitoring the infrared linear dichroism spectra in the course of H-1/H-2 exchange allowed to focus the recording of exchange rates on the membrane-embedded region of the protein only. This approach revealed an unusual structural dynamics, indicating high flexibility in this antibiotic binding and transport region.

Original languageEnglish
Pages (from-to)11876-11886
Number of pages11
JournalBiochemistry
Volume40
Issue number39
Publication statusPublished - 2-Oct-2001

Keywords

  • TRANSFORM INFRARED-SPECTROSCOPY
  • HYDROGEN-DEUTERIUM EXCHANGE
  • RESISTANCE P-GLYCOPROTEIN
  • TERTIARY STRUCTURE CHANGES
  • AMIDE-PROTON EXCHANGE
  • SECONDARY STRUCTURE
  • MULTIDRUG-RESISTANCE
  • PHOSPHOLIPID-MEMBRANES
  • CONFORMATIONAL-CHANGES
  • ANTIBIOTIC-RESISTANCE

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