Characterization of the ABC methionine transporter from Neisseria meningitidis reveals that lipidated MetQ is required for interaction
- Howard Hughes Medical Institute, California Institute of Technology, United States
- California Institute of Technology, United States
Abstract
NmMetQ is a substrate-binding protein (SBP) from Neisseria meningitidis that has been identified as a surface-exposed candidate antigen for meningococcal vaccines. However, this location for NmMetQ challenges the prevailing view that SBPs in Gram-negative bacteria are localized to the periplasmic space to promote interaction with their cognate ABC transporter embedded in the bacterial inner membrane. To elucidate the roles of NmMetQ, we characterized NmMetQ with and without its cognate ABC transporter (NmMetNI). Here, we show that NmMetQ is a lipoprotein (lipo-NmMetQ) that binds multiple methionine analogs and stimulates the ATPase activity of NmMetNI. Using single-particle electron cryo-microscopy, we determined the structures of NmMetNI in the presence and absence of lipo-NmMetQ. Based on our data, we propose that NmMetQ tethers to membranes via a lipid anchor and has dual function and localization, playing a role in NmMetNI-mediated transport at the inner membrane and moonlighting on the bacterial surface.
Data availability
For NmMetNI in the inward-facing conformation and lipo-NmMetQ:NmMetNI complex in the outward-facing conformation, cryoEM maps have been deposited in the Electron Microscopy Data Bank (EMDB) under accession codes EMD-23752 and EMD-23751. Coordinates for the model are deposited in the Research Collaboratory for Structural Bioinformatics Protein Data Bank under accession numbers 7MC0 and 7MBZ, respectively.
Article and author information
Author details
David G VanderVelde
Funding
Burroughs Wellcome Fund
- Naima G Sharaf
Howard Hughes Medical Institute
- Douglas C Rees
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Sharaf et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Characterization of the ABC methionine transporter from Neisseria meningitidis reveals that lipidated MetQ is required for interaction
eLife 10:e69742.
https://doi.org/10.7554/eLife.69742
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