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Structural mechanism of phospholipids translocation by MlaFEDB complex
Ximin Chi1,2, Qiongxuan Fan1,2, Yuanyuan Zhang1,2
1Center for Infectious Disease Research, Zhejiang Provincial Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China.
Cell Research
|September 5, 2020
Summary
The MlaFEDB complex in Gram-negative bacteria moves phospholipids across membranes. Structural studies reveal its mechanism for maintaining bacterial phospholipid homeostasis and the dual-membrane barrier.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Phospholipids are crucial for Gram-negative bacteria's dual-membrane barrier, impacting antibiotic resistance.
- Understanding phospholipid translocation is key to bacterial phospholipid homeostasis.
Purpose of the Study:
- To elucidate the mechanism of phospholipid translocation mediated by the MlaFEDB complex.
- To determine the structural basis of MlaFEDB function in phospholipid transport.
Main Methods:
- Determined three cryo-electron microscopy (cryo-EM) structures of the MlaFEDB complex from Escherichia coli.
- Performed extensive functional studies to validate structural findings.
Main Results:
- Revealed unique structural features of the MlaFEDB complex in nucleotide-free and ATP-bound states.
- Identified six phospholipids within three distinct cavities of the complex.
- Observed large-scale conformational changes upon ATP binding, defining the complex's functional cycle.
Conclusions:
- The MlaFEDB complex utilizes an extrusion mechanism to translocate phospholipids.
- This mechanism is essential for maintaining bacterial phospholipid homeostasis and the integrity of the dual-membrane barrier.
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