Published online August 25, 2008
doi:10.1083/jcb.200804131
The Journal of Cell Biology, Vol. 182, No. 4, 741-752
The Rockefeller University Press, 0021-9525 $30.00
© 2008 Mallo et al.
SopB promotes phosphatidylinositol 3-phosphate formation on Salmonella vacuoles by recruiting Rab5 and Vps34
Gustavo V. Mallo1,
Marianela Espina1,
Adam C. Smith1,
Mauricio R. Terebiznik2,
Ainel Alemán6,
B. Brett Finlay7,8,9,
Lucia E. Rameh10,
Sergio Grinstein1,3,4, and
John H. Brumell1,4,5
1 Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
2 Department of Biological Sciences, 3 Department of Biochemistry, 4 Institute of Medical Science, and 5 Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
6 Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, 280040 Madrid, Spain
7 Michael Smith Laboratory, 8 Department of Biochemistry and Molecular Biology, and 9 Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
10 Boston Biomedical Research Institute, Watertown, MA 02472
Correspondence to John H. Brumell: john.brumell{at}sickkids.ca
Salmonella colonizes a vacuolar niche in host cells during infection. Maturation of the Salmonella-containing vacuole (SCV) involves the formation of phosphatidylinositol 3-phosphate (PI(3)P) on its outer leaflet. SopB, a bacterial virulence factor with phosphoinositide phosphatase activity, was proposed to generate PI(3)P by dephosphorylating PI(3,4)P2, PI(3,5)P2, and PI(3,4,5)P3. Here, we examine the mechanism of PI(3)P formation during Salmonella infection. SopB is required to form PI(3,4)P2/PI(3,4,5)P3 at invasion ruffles and PI(3)P on nascent SCVs. However, we uncouple these events experimentally and reveal that SopB does not dephosphorylate PI(3,4)P2/PI(3,4,5)P3 to produce PI(3)P. Instead, the phosphatase activity of SopB is required for Rab5 recruitment to the SCV. Vps34, a PI3-kinase that associates with active Rab5, is responsible for PI(3)P formation on SCVs. Therefore, SopB mediates PI(3)P production on the SCV indirectly through recruitment of Rab5 and its effector Vps34. These findings reveal a link between phosphoinositide phosphatase activity and the recruitment of Rab5 to phagosomes.
Abbreviations used in this paper: ESI-MS, electrospray ionization mass spectrometry; PH, pleckstrin homology; PI, phosphatidylinositol; PI(3)P, PI 3-phosphate; PIP, PI phosphate; PIP2, PI bisphosphate; SCV, Salmonella-containing vacuole; SPI, Salmonella pathogenicity island; T3SS, type III secretion system; WT, wild type.
© 2008 Mallo et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
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