An octameric PqiC toroid stabilises the outer-membrane interaction of the PqiABC transport system

Benjamin F Cooper, Giedrė Ratkevičiūtė, Luke A Clifton, Hannah Johnston, Rachel Holyfield, David J Hardy, Simon G Caulton, William Chatterton, Pooja Sridhar, Peter Wotherspoon, Gareth W Hughes, Stephen Cl Hall, Andrew L Lovering, Timothy J Knowles*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

The E. coli Paraquat Inducible (Pqi) Pathway is a putative Gram-negative phospholipid transport system. The pathway comprises three components: an integral inner membrane protein (PqiA), a periplasmic spanning MCE family protein (PqiB) and an outer membrane lipoprotein (PqiC). Interactions between all complex components, including stoichiometry, remain uncharacterised; nevertheless, once assembled into their quaternary complex, the trio of Pqi proteins are anticipated to provide a continuous channel between the inner and outer membranes of diderms. Here, we present X-ray structures of both the native and a truncated, soluble construct of the PqiC lipoprotein, providing insight into its biological assembly, and utilise neutron reflectometry to characterise the nature of the PqiB-PqiC-membrane interaction. Finally, we employ phenotypic complementation assays to probe specific PqiC residues, which imply the interaction between PqiB and PqiC is less intimate than previously anticipated.

Original languageEnglish
Pages (from-to)82-101
Number of pages20
JournalEMBO Reports
Volume25
Issue number1
DOIs
Publication statusPublished - 12 Jan 2024

Bibliographical note

Acknowledgements:
We wish to thank the funding bodies who support us, BFC, GR, HJ, RH and PW were/are jointly funded by the BBSRC and the University of Birmingham (through the Midlands Integrative Biosciences Training Partnership - Grant No.BB/M01116X/1). DJH, GWH and TJK were supported by BBSRC Research Grant No. BB/S017283/1. We thank the Science and Technology Facilities Council, the ISIS Neutron & Muon Source for allocation of beamtime (RB2300004 and RB2220703) and Diamond Light Source for access to beamline I04 under proposal number mx26803.

© 2024. The Author(s).

Keywords

  • Lipid Transport
  • Outer Membrane Biogenesis
  • Gram NegativeCell Envelope
  • Pqi
  • Envelope Spanning

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