The lipid environment determines the activity of the Escherichia coli ammonium transporter AmtB
Dias Mirandela, Gaëtan and Tamburrino, Giulia and Hoskisson, Paul A. and Zachariae, Ulrich and Javelle, Arnaud (2019) The lipid environment determines the activity of the Escherichia coli ammonium transporter AmtB. FASEB Journal, 33 (2). pp. 1989-1999. ISSN 0892-6638 (https://doi.org/10.1096/fj.201800782R)
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Abstract
The movement of ammonium across biologic membranes is a fundamental process in all living organisms and is mediated by the ubiquitous ammonium transporter/methylammonium permease/rhesus protein (Amt/Mep/Rh) family of transporters. Recent structural analysis and coupled mass spectrometry studies have shown that the Escherichia coli ammonium transporter AmtB specifically binds 1-palmitoyl-2-oleoyl phosphatidylglycerol (POPG). Upon POPG binding, several residues of AmtB undergo a small conformational change, which stabilizes the protein against unfolding. However, no studies have so far been conducted, to our knowledge, to explore whether POPG binding to AmtB has functional consequences. Here, we used an in vitro experimental assay with purified components, together with molecular dynamics simulations, to characterize the relation between POPG binding and AmtB activity. We show that the AmtB activity is electrogenic. Our results indicate that the activity, at the molecular level, of Amt in archaebacteria and eubacteria may differ. We also show that POPG is an important cofactor for AmtB activity and that, in the absence of POPG, AmtB cannot complete the full translocation cycle. Furthermore, our simulations reveal previously undiscovered POPG binding sites on the intracellular side of the lipid bilayer between the AmtB subunits. Possible molecular mechanisms explaining the functional role of POPG are discussed.-Mirandela, G. D., Tamburrino, G., Hoskisson, P. A., Zachariae, U., Javelle, A. The lipid environment determines the activity of the Escherichia coli ammonium transporter AmtB.
ORCID iDs
Dias Mirandela, Gaëtan ORCID: https://orcid.org/0000-0001-5871-6288, Tamburrino, Giulia, Hoskisson, Paul A. ORCID: https://orcid.org/0000-0003-4332-1640, Zachariae, Ulrich and Javelle, Arnaud ORCID: https://orcid.org/0000-0002-3611-5737;-
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Item type: Article ID code: 65171 Dates: DateEvent28 February 2019Published13 September 2018Published Online14 August 2018AcceptedSubjects: Science > Microbiology
Medicine > Therapeutics. PharmacologyDepartment: Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences Depositing user: Pure Administrator Date deposited: 15 Aug 2018 10:01 Last modified: 13 Oct 2024 00:35 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/65171