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Eukaryotic Cell, August 2008, p. 1256-1267, Vol. 7, No. 8
1535-9778/08/$08.00+0     doi:10.1128/EC.00090-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Leishmania Adaptor Protein-1 Subunits Are Required for Normal Lysosome Traffic, Flagellum Biogenesis, Lipid Homeostasis, and Adaptation to Temperatures Encountered in the Mammalian Host ^,

James E. Vince,^1, Dedreia L. Tull,^1,3 Timothy Spurck,² Merran C. Derby,^1,3 Geoffrey I. McFadden,² Paul A. Gleeson,^1,3 Suzanne Gokool,⁴ and Malcolm J. McConville^1,3*

Department of Biochemistry and Molecular Biology,¹ School of Botany, University of Melbourne, Royal Parade, Parkville, Victoria, Australia,² Bio21 Molecular Science and Biotechnology Institute, Flemington Rd., Parkville, Victoria, Australia,³ Cambridge Institute for Medical Research, Addenbrooke's Hospital, Hills Road, Cambridge, United Kingdom⁴

Received 12 March 2008/ Accepted 16 May 2008

The adaptor protein-1 (AP-1) complex is involved in membrane transport between the Golgi apparatus and endosomes. In the protozoan parasite Leishmania mexicana mexicana, the AP-1 µ1 and 1 subunits are not required for growth at 27°C but are essential for infectivity in the mammalian host. In this study, we have investigated the function of these AP-1 subunits in order to understand the molecular basis for this loss of virulence. The µ1 and 1 subunits were localized to late Golgi and endosome membranes of the major parasite stages. Parasite mutants lacking either AP-1 subunit lacked obvious defects in Golgi structure, endocytosis, or exocytic transport. However, these mutants displayed reduced rates of endosome-to-lysosome transport and accumulated fragmented, sterol-rich lysosomes. Defects in flagellum biogenesis were also evident in nondividing promastigote stages, and this phenotype was exacerbated by inhibitors of sterol and sphingolipid biosynthesis. Furthermore, both AP-1 mutants were hypersensitive to elevated temperature and perturbations in membrane lipid composition. The pleiotropic requirements for AP-1 in membrane trafficking and temperature stress responses explain the loss of virulence of these mutants in the mammalian host.

Published ahead of print on 30 May 2008.

Supplemental material for this article may be found at http://ec.asm.org/.

Present address: Department of Biochemistry, La Trobe University, Bundoora, Victoria, Australia.