University of Massachusetts Medical School Faculty Publications

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology

Publication Date

2021-04-08

Document Type

Article Preprint

Disciplines

Amino Acids, Peptides, and Proteins | Bacteria | Biochemistry, Biophysics, and Structural Biology | Microbiology

Abstract

Present in all bacteria, lipoproteins are central in bacterial growth and antibiotic resistance. These proteins use lipid acyl chains attached to the N-terminal cysteine residue to anchor on the outer surface of cytoplasmic membrane. In Gram-negative bacteria, many lipoproteins are transported to the outer membrane (OM), a process dependent on the ATP-binding cassette (ABC) transporter LolCDE which extracts the OM-targeted lipoproteins from the cytoplasmic membrane for subsequent trafficking across the periplasm. Lipid-anchored proteins pose a unique challenge for transport machinery as they have both hydrophobic lipid moieties and soluble protein component, and the underlying mechanism is poorly understood. Here we determined the cryo-EM structures of nanodisc-embedded LolCDE in the nucleotide-free and nucleotide-bound states at 3.8-Å and 3.5-Å resolution, respectively. The structural analyses, together with biochemical and mutagenesis studies, uncover how LolCDE specifically recognizes its substrate by establishing multiple interactions with the lipid and N-terminal peptide moieties of the lipoprotein, and identify the amide-linked acyl chain as the key element for LolCDE interaction. Upon nucleotide binding, the transmembrane helices and the periplasmic domains of LolCDE undergo large-scale, asymmetric movements, resulting in extrusion of the captured lipoprotein. Comparison of LolCDE and MacB reveals the conserved mechanism of type VII ABC transporters and emphasizes the unique properties of LolCDE as a molecule extruder of triacylated lipoproteins.

Keywords

Microbiology, antibiotic resistance, nucleotides, structure

Rights and Permissions

The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license.

DOI of Published Version

10.1101/2021.04.06.438740

Source

bioRxiv 2021.04.06.438740; doi: https://doi.org/10.1101/2021.04.06.438740. Link to preprint on bioRxiv.

Comments

This article is a preprint. Preprints are preliminary reports of work that have not been certified by peer review.

Journal/Book/Conference Title

bioRxiv

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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