SdhA blocks disruption of the Legionella-containing vacuole by hijacking the OCRL phosphatase
Won Young Choi,
Seongok Kim,
Philipp Aurass,
Wenwen Huo,
Elizabeth A. Creasey,
Marc Edwards,
Martin Lowe,
Ralph R. Isberg
Affiliations
Won Young Choi
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA
Seongok Kim
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA
Philipp Aurass
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA; Division of Enteropathogenic Bacteria and Legionella (FG11), Robert Koch-Institut, Wernigerode, Germany
Wenwen Huo
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA
Elizabeth A. Creasey
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA
Marc Edwards
Department of Biology, Amherst College, Amherst, MA 01002, USA
Martin Lowe
School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
Ralph R. Isberg
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA; Corresponding author
Summary: Legionella pneumophila grows intracellularly within a replication vacuole via action of Icm/Dot-secreted proteins. One such protein, SdhA, maintains the integrity of the vacuolar membrane, thereby preventing cytoplasmic degradation of bacteria. We show here that SdhA binds and blocks the action of OCRL (OculoCerebroRenal syndrome of Lowe), an inositol 5-phosphatase pivotal for controlling endosomal dynamics. OCRL depletion results in enhanced vacuole integrity and intracellular growth of a sdhA mutant, consistent with OCRL participating in vacuole disruption. Overexpressed SdhA alters OCRL function, enlarging endosomes, driving endosomal accumulation of phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2), and interfering with endosomal trafficking. SdhA interrupts Rab guanosine triphosphatase (GTPase)-OCRL interactions by binding to the OCRL ASPM-SPD2-Hydin (ASH) domain, without directly altering OCRL 5-phosphatase activity. The Legionella vacuole encompassing the sdhA mutant accumulates OCRL and endosomal antigen EEA1 (Early Endosome Antigen 1), consistent with SdhA blocking accumulation of OCRL-containing endosomal vesicles. Therefore, SdhA hijacking of OCRL is associated with blocking trafficking events that disrupt the pathogen vacuole.
