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Updated: Jan 21, 2026
Electroporation of Mycobacteria
Published on: May 23, 2008
The MmpL3 interactome reveals a complex crosstalk between cell envelope biosynthesis and cell elongation and division
Juan Manuel Belardinelli1, Casey M Stevens2, Wei Li1
1Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, 80523-1682, USA.
Abstract:
Integral membrane transporters of the Mycobacterial Membrane Protein Large (MmpL) family and their interactome play important roles in the synthesis and export of mycobacterial outer membrane lipids. Despite the current interest in the mycolic acid transporter, MmpL3, from the perspective of drug discovery, the nature and biological significance of its interactome remain largely unknown. We here report on a genome-wide screening by two-hybrid system for MmpL3 binding partners. While a surprisingly low number of proteins involved in mycolic acid biosynthesis was found to interact with MmpL3, numerous enzymes and transporters participating in the biogenesis of peptidoglycan, arabinogalactan and lipoglycans, and the cell division regulatory protein, CrgA, were identified among the hits. Surface plasmon resonance and co-immunoprecipitation independently confirmed physical interactions for three proteins in vitro and/or in vivo. Results are in line with the focal localization of MmpL3 at the poles and septum of actively-growing bacilli where the synthesis of all major constituents of the cell wall core are known to occur, and are further suggestive of a role for MmpL3 in the coordination of new cell wall deposition during cell septation and elongation. This novel aspect of the physiology of MmpL3 may contribute to the extreme vulnerability and high therapeutic potential of this transporter.
Insights
The Mycobacterial Membrane Protein Large 3 (MmpL3) transporter interacts with cell wall components, not just mycolic acids. This finding suggests MmpL3
Area of Science:
- Microbiology
- Molecular Biology
- Drug Discovery
Background:
- Integral membrane transporters of the Mycobacterial Membrane Protein Large (MmpL) family are crucial for mycobacterial outer membrane lipid synthesis and export.
- The mycolic acid transporter, MmpL3, is a key drug discovery target, but its interactome and biological significance are poorly understood.
Purpose of the Study:
- To identify MmpL3 binding partners using a genome-wide screening approach.
- To elucidate the biological significance of the MmpL3 interactome in mycobacterial physiology.
Main Methods:
- Genome-wide two-hybrid screening to identify MmpL3 interacting proteins.
- Surface plasmon resonance and co-immunoprecipitation for validation of physical interactions.
Main Results:
- A limited number of mycolic acid biosynthesis proteins interacted with MmpL3.
- Numerous enzymes and transporters involved in peptidoglycan, arabinogalactan, and lipoglycan biogenesis were identified as MmpL3 interactors.
- The cell division regulator CrgA was also identified as an MmpL3 binding partner.
- Physical interactions were confirmed in vitro and/or in vivo for three identified proteins.
Conclusions:
- MmpL3 interacts with a broader range of cell wall biogenesis proteins than previously known.
- MmpL3's localization at the cell poles and septum supports its role in coordinating cell wall deposition during cell division.
- This newly identified physiological role of MmpL3 highlights its potential as a therapeutic target.
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