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Proc Natl Acad Sci U S A. 2016 Feb 16;113(7):1901-6. doi: 10.1073/pnas.1522067113. Epub 2016 Feb 1.

Legionella pneumophila S1P-lyase targets host sphingolipid metabolism and restrains autophagy.

Author information

1
Institut Pasteur, Biologie des Bactéries Intracellulaires, 75724 Paris, France; CNRS UMR 3525, 75724 Paris, France;
2
Institut Necker Enfants-Malades, INSERM U1151-CNRS UMR 8253, 75993 Paris, France; Université Paris Descartes-Sorbonne Paris Cité, 75993 Paris, France;
3
INSERM UMR1037, Centre de Recherches en Cancérologie de Toulouse, 31432 Toulouse, France;
4
Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada M5S 3E5;
5
Department of Biochemistry and Molecular Biology and the Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia;
6
Institute of Medical Microbiology, University of Zürich, 8006, Zurich, Switzerland;
7
Metabolomics Australia, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia;
8
Metabolomics Australia, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC 3010, Australia;
9
Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3010, Australia.
10
Institut Pasteur, Biologie des Bactéries Intracellulaires, 75724 Paris, France; CNRS UMR 3525, 75724 Paris, France; cbuch@pasteur.fr.

Abstract

Autophagy is an essential component of innate immunity, enabling the detection and elimination of intracellular pathogens. Legionella pneumophila, an intracellular pathogen that can cause a severe pneumonia in humans, is able to modulate autophagy through the action of effector proteins that are translocated into the host cell by the pathogen's Dot/Icm type IV secretion system. Many of these effectors share structural and sequence similarity with eukaryotic proteins. Indeed, phylogenetic analyses have indicated their acquisition by horizontal gene transfer from a eukaryotic host. Here we report that L. pneumophila translocates the effector protein sphingosine-1 phosphate lyase (LpSpl) to target the host sphingosine biosynthesis and to curtail autophagy. Our structural characterization of LpSpl and its comparison with human SPL reveals high structural conservation, thus supporting prior phylogenetic analysis. We show that LpSpl possesses S1P lyase activity that was abrogated by mutation of the catalytic site residues. L. pneumophila triggers the reduction of several sphingolipids critical for macrophage function in an LpSpl-dependent and -independent manner. LpSpl activity alone was sufficient to prevent an increase in sphingosine levels in infected host cells and to inhibit autophagy during macrophage infection. LpSpl was required for efficient infection of A/J mice, highlighting an important virulence role for this effector. Thus, we have uncovered a previously unidentified mechanism used by intracellular pathogens to inhibit autophagy, namely the disruption of host sphingolipid biosynthesis.

KEYWORDS:

Legionella pneumophila; autophagy; sphingolipids; sphingosine-1-phosphate lyase; virulence

PMID:
26831115
PMCID:
PMC4763766
DOI:
10.1073/pnas.1522067113
[Indexed for MEDLINE]
Free PMC Article

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