Quick Search:

uzh logo
Browse by:
bullet
bullet
bullet
bullet

Zurich Open Repository and Archive 

Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-19624

Seeger, M A; von Ballmoos, C; Verrey, F; Pos, K M (2009). Crucial role of Asp408 in the proton translocation pathway of multidrug transporter AcrB: evidence from site-directed mutagenesis and carbodiimide labeling. Biochemistry, 48(25):5801-5812.

[img] PDF - Registered users only
1MB

Abstract

The three-component AcrA/AcrB/TolC efflux system of Escherichia coli catalyzes the proton motive force-driven extrusion of a variety of cytotoxic compounds. The inner membrane pump component AcrB belongs to the resistance nodulation and cell division (RND) superfamily and is responsible for drug specificity and energy transduction of the entire tripartite efflux system. Systematic mutational analysis of titratable and polar membrane-located amino acids revealed four residues, D407, D408, K940, and, R971, to be of prime importance for AcrB function. Using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, D408 was shown to specifically react with dicyclohexylcarbodiimide (DCCD) in a pH-dependent manner. The apparent pK(a) of D408 of 7.4 would enable binding and release of protons under physiological conditions. In contrast to other secondary transporters, D408 was not protected from carbodiimide modification in the presence of drugs, which supports the notion of spatially separated transport pathways for drugs and protons. This study provides evidence for a substantial role of membrane-located carboxylates as a central element of the proton translocation pathway in AcrB and other members of the RND superfamily.

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Integrative Human Physiology
04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
DDC:570 Life sciences; biology
610 Medicine & health
Language:English
Date:30 June 2009
Deposited On:08 Jul 2009 06:46
Last Modified:27 Nov 2013 22:11
Publisher:American Chemical Society
ISSN:0006-2960
Publisher DOI:10.1021/bi900446j
PubMed ID:19425588
Citations:Web of Science®. Times Cited: 20
Google Scholar™
Scopus®. Citation Count: 24

Users (please log in): suggest update or correction for this item

Repository Staff Only: item control page