Premium
Non‐equivalent roles of two periplasmic subunits in the function and assembly of triclosan pump TriABC from P seudomonas aeruginosa
Author(s) -
Weeks Jon W.,
Nickels Logan M.,
Ntreh Abigail T.,
Zgurskaya Helen I.
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13124
Subject(s) - efflux , triclosan , periplasmic space , biology , transporter , bacterial outer membrane , pseudomonas aeruginosa , biochemistry , function (biology) , bacteria , membrane transport protein , microbiology and biotechnology , escherichia coli , gene , genetics , medicine , pathology
Summary In Gram‐negative bacteria, multidrug efflux transporters function in complexes with periplasmic membrane fusion proteins ( MFPs ) that enable antibiotic efflux across the outer membrane. In this study, we analyzed the function, composition and assembly of the triclosan efflux transporter TriABC – OpmH from P seudomonas aeruginosa . We report that this transporter possesses a surprising substrate specificity that encompasses not only triclosan but the detergent SDS , which are often used together in antibacterial soaps. These two compounds interact antagonistically in a TriABC ‐dependent manner and negate antibacterial properties of each other. Unlike other efflux pumps that rely on a single MFP for their activities, two different MFPs , TriA and TriB , are required for triclosan/ SDS resistance mediated by TriABC – OpmH . We found that analogous mutations in the α‐helical hairpin and membrane proximal domains of TriA and TriB differentially affect triclosan efflux and assembly of the complex. Furthermore, our results show that TriA and TriB function as a dimer, in which TriA is primarily responsible for stabilizing interactions with the outer membrane channel, whereas TriB is important for the stimulation of the transporter. We conclude that MFPs are engaged into complexes as asymmetric dimers, in which each protomer plays a specific role.