The mycobacterium lipid transporter MmpL3 is dimeric in detergent solution, SMALPs and reconstituted nanodiscs
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
The mycobacterial membrane protein large 3 (MmpL3) transports key precursor lipids to the outer membrane of Mycobacterium species. Multiple structures of MmpL3 from both M. tuberculosis and M. smegmatis in various conformational states indicate that the protein is both structurally and functionally monomeric. However, most other resistance, nodulation and cell division (RND) transporters structurally characterised to date are either dimeric or trimeric. Here we present an in depth biophysical and computational analysis revealing that MmpL3 from M. smegmatis exists as a dimer in a variety of membrane mimetic systems (SMALPs, detergent-based solution and nanodiscs). Sucrose gradient separation of MmpL3 populations from M. smegmatis, reconstituted into nanodiscs, identified monomeric and dimeric populations of the protein using laser induced liquid bead ion desorption (LILBID), a native mass spectrometry technique. Preliminary cryo-EM analysis confirmed that MmpL3 forms physiological dimers. Untargeted lipidomics experiments on membrane protein co-purified lipids revealed PE and PG lipid classes were predominant. Molecular dynamics simulations, in the presence of physiologically-relevant lipid compositions revealed the likely dimer interface.
Date Issued
2024-09-01
Date Acceptance
2024-07-26
Citation
RSC Chemical Biology, 2024, 5 (9), pp.901-913
ISSN
2633-0679
Publisher
The Royal Society of Chemistry
Start Page
901
End Page
913
Journal / Book Title
RSC Chemical Biology
Volume
5
Issue
9
Copyright Statement
© Royal Society of Chemistry 2024. Open Access Article. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
License URL
Identifier
https://pubs.rsc.org/en/Content/ArticleLanding/2024/CB/D4CB00110A
Publication Status
Published
Date Publish Online
2024-07-29