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Title: MmpL3 is a lipid transporter that binds trehalose monomycolate and phosphatidylethanolamine

Journal Article · · Proceedings of the National Academy of Sciences of the United States of America

The cell envelope of Mycobacterium tuberculosis is notable for the abundance of mycolic acids (MAs), essential to mycobacterial viability, and of other species-specific lipids. The mycobacterial cell envelope is extremely hydrophobic, which contributes to virulence and antibiotic resistance. However, exactly how fatty acids and lipidic elements are transported across the cell envelope for cell-wall biosynthesis is unclear. Mycobacterial membrane protein Large 3 (MmpL3) is essential and required for transport of trehalose monomycolates (TMMs), precursors of MA-containing trehalose dimycolates (TDM) and mycolyl arabinogalactan peptidoglycan, but the exact function of MmpL3 remains elusive. Here, we report a crystal structure of Mycobacterium smegmatis MmpL3 at a resolution of 2.59 Å, revealing a monomeric molecule that is structurally distinct from all known bacterial membrane proteins. A previously unknown MmpL3 ligand, phosphatidylethanolamine (PE), was discovered inside this transporter. We also show, via native mass spectrometry, that MmpL3 specifically binds both TMM and PE, but not TDM, in the micromolar range. These observations provide insight into the function of MmpL3 and suggest a possible role for this protein in shuttling a variety of lipids to strengthen the mycobacterial cell wall.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
National Institutes of Health (NIH)
OSTI ID:
1531017
Report Number(s):
AC02-06CH11357
Journal Information:
Proceedings of the National Academy of Sciences of the United States of America, Vol. 116, Issue 23; ISSN 0027-8424
Publisher:
National Academy of SciencesCopyright Statement
Country of Publication:
United States
Language:
ENGLISH
Citation Metrics:
Cited by: 63 works
Citation information provided by
Web of Science

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Cited By (8)

AcrB: a mean, keen, drug efflux machine journal September 2019
Identification of novel scaffolds targeting Mycobacterium tuberculosis text January 2019
Promiscuous Targets for Antitubercular Drug Discovery: The Paradigm of DprE1 and MmpL3 journal January 2020
Identification of novel scaffolds targeting Mycobacterium tuberculosis journal November 2019
Identification of New MmpL3 Inhibitors by Untargeted and Targeted Mutant Screens Defines MmpL3 Domains with Differential Resistance journal August 2019
The MmpL3 interactome reveals a complex crosstalk between cell envelope biosynthesis and cell elongation and division in mycobacteria journal July 2019
A piperidinol-containing molecule is active against Mycobacterium tuberculosis by inhibiting the mycolic acid flippase activity of MmpL3 journal September 2019
The crystal structure of the mycobacterial trehalose monomycolate transport factor A, TtfA, reveals an atypical fold journal December 2019