Structure-function analysis of the ATP-driven glycolipid efflux pump DevBCA reveals complex organization with...

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• Trans-envelope efflux pumps in Gram-negative bacteria utilize membrane fusion proteins (MFPs) to mediate interactions between outer membrane factors (OMFs) and inner membrane factors (IMFs).
• Understanding the structure-function relationships of these pumps is vital for deciphering transport mechanisms and developing novel antimicrobial strategies.

Purpose of the Study:

• To investigate the structure-function relationships of the ATP-driven glycolipid efflux pump DevBCA-TolC/HgdD from the cyanobacterium Anabaena sp. PCC 7120.
• To elucidate the specific roles of the membrane fusion protein DevB in the assembly and function of the efflux pump.

Main Methods:

• Structural analysis of protein-protein interactions within the DevBCA-TolC/HgdD efflux pump complex.
• Biochemical assays to assess binding affinities and functional activity of pump components.

Main Results:

• The binding of the membrane fusion protein (MFP) DevB to the outer membrane factor (OMF) TolC critically depends on their respective tip regions.
• The interaction between DevB and the inner membrane factor (IMF) DevAC primarily involves the β-barrel and lipoyl domains of DevB.
• Stable hexameric structures of DevB are indispensable for efficient binding to DevAC and TolC, substrate recognition, and export activity mediated by DevAC.

Conclusions:

• The study highlights the critical role of DevB hexamer stability in the overall function of the DevBCA-TolC/HgdD efflux pump.
• Specific domains of DevB mediate distinct interactions with OMF and IMF components, providing insights into the assembly and mechanism of trans-envelope pumps.