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Bacterial Metal Resistance: Coping with Copper without Cooperativity?
Nicholas P Greene1, Vassilis Koronakis1
1Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
Mbio
|June 15, 2021
Summary
Tripartite efflux pumps (TEPs) in bacteria like Escherichia coli remove toxins. New research on CusA reveals its monomers may work independently, challenging previous models of these essential bacterial transporters.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Tripartite efflux pumps (TEPs) are crucial for removing toxic substances from Gram-negative bacteria.
- The CusBCA system in Escherichia coli utilizes the resistance-nodulation-cell division (RND) transporter CusA for copper and silver detoxification.
- Understanding TEP mechanisms is vital for bacterial survival and combating antibiotic resistance.
Purpose of the Study:
- To investigate the structural mechanism of the CusA trimer in Escherichia coli.
- To determine if CusA monomers function independently or cooperatively during transport.
- To compare the functional mechanism of CusA with other RND transporters like AcrB.
Main Methods:
- Cryo-electron microscopy (cryo-EM) was used to obtain high-resolution structures of CusA trimers.
- Analysis of multiple CusA conformations in the presence of copper.
- Comparative structural analysis with other RND transporters.
Main Results:
- Cryo-EM revealed multiple conformations of the CusA trimer.
- The observed conformations suggest independent functional activity of the three CusA monomers.
- This contrasts with the proposed cooperative mechanism of the multidrug transporter AcrB.
Conclusions:
- The findings challenge the prevailing model of cooperative function in RND transporters.
- CusA may operate via an independent monomer mechanism, offering new insights into TEP function.
- This study provides a structural basis for future research on TEPs involved in bacterial detoxification and survival.
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