The Mla pathway in Acinetobacter baumannii has no demonstrable role in anterograde lipid transport

Abstract
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Abstract

The asymmetric outer membrane (OM) of Gram-negative bacteria functions as a selective permeability barrier to the environment. Perturbations to OM lipid asymmetry sensitize the cell to antibiotics. As such, mechanisms involved in lipid asymmetry are fundamental to our understanding of OM lipid homeostasis. One such mechanism, the Maintenance of lipid asymmetry (Mla) pathway has been proposed to extract mislocalized glycerophospholipids from the outer leaflet of the OM and return them to the inner membrane (IM). Work on this pathway in Acinetobacter baumannii support conflicting models for the directionality of the Mla system being retrograde (OM to IM) or anterograde (IM to OM). Here we show conclusively that A. baumannii mla mutants exhibit no defects in anterograde transport. Furthermore, we identify an allele of the GTPase obgE that is synthetically sick in the absence of Mla; providing another link between cell envelope homeostasis and stringent response.

Data availability

Sequencing data (RNAseq) have been deposited to the database NCBI Gene Expression Omnibus. Accession number is GSE147139

The following data sets were generated

(2020) RNAseq of Mla mutants
NCBI Gene Expression Omnibus, GSE147139.

https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE147139

Article and author information

Author details

Matthew J Powers

Microbiology, University of Georgia, Athens, United States

Competing interests
The authors declare that no competing interests exist.
Brent W Simpson

Infectious Diseases, University of Georgia, Athens, United States

Competing interests
The authors declare that no competing interests exist.
M Stephen Trent

Infectious Diseases, Microbiology, University of Georgia, Athens, United States

For correspondence
strent@uga.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-6134-1800

Funding

National Institute of Allergy and Infectious Diseases (AI129940)

M Stephen Trent

National Institute of Allergy and Infectious Diseases (AI138576)

M Stephen Trent

National Institute of Allergy and Infectious Diseases (AI150098)

M Stephen Trent

National Science Foundation (049347-06)

Matthew J Powers

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

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.