Phospholipid translocation captured in a bifunctional membrane protein MprF

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• Multiple Peptide Resistance Factors (MprFs) are essential membrane proteins in bacteria.
• MprFs are critical for bacterial physiology, virulence, and resistance to antibiotics like daptomycin.
• They function by synthesizing and translocating aminoacyl phospholipids.

Purpose of the Study:

• To elucidate the structural basis of MprF function.
• To understand the mechanism of phospholipid translocation and modification by MprF.
• To provide a framework for MprF-mediated antibiotic resistance.

Main Methods:

• Cryo-electron microscopy (cryo-EM) was used to determine the structures of RtMprF.
• Structures were obtained for MprF in complex with lysyl-phosphatidylglycerol (LysPG).
• Analysis of MprF homodimer from Rhizobium tropici (RtMprF) in multiple conformational states.

Main Results:

• Detailed cryo-EM structures of RtMprF homodimer were presented.
• A membrane-embedded lipid-flippase domain with two cavities was identified.
• LysPG was observed trapped within the inner cavity, with its head group oriented towards the outer cavity.
• Multiple conformational states of the synthase and flippase domains were revealed.

Conclusions:

• The study provides a detailed structural framework for MprF function.
• Insights into the mechanism of MprF-mediated phospholipid translocation and modification were gained.
• Understanding MprF mechanisms can inform strategies against bacterial antibiotic resistance.