title: Ecotin-like serine peptidase inhibitor ISP1 of Leishmania major plays a role in flagellar pocket dynamics and promastigote differentiation.
abstract: Leishmania ISPs are ecotin-like natural peptide inhibitors of trypsin-family serine peptidases, enzymes that are absent from the Leishmania genome. This led to the proposal that ISPs inhibit host serine peptidases and we have recently shown that ISP2 inhibits neutrophil elastase, thereby enhancing parasite survival in murine macrophages. In this study we show that ISP1 has less serine peptidase inhibitory activity than ISP2, and in promastigotes both are generally located in the cytosol and along the flagellum. However, in haptomonad promastigotes there is a prominent accumulation of ISP1 and ISP2 in the hemidesmosome and for ISP2 on the cell surface. An L. major mutant deficient in all three ISP genes (Δisp1/2/3) was generated and compared with Δisp2/3 mutants to elucidate the physiological role of ISP1. In in vitro cultures, the Δisp1/2/3 mutant contained more haptomonad, nectomonad and leptomonad promastigotes with elongated flagella and reduced motility compared with Δisp2/3 populations, moreover it was characterized by very high levels of release of exosome-like vesicles from the flagellar pocket. These data suggest that ISP1 has a primary role in flagellar homeostasis, disruption of which affects differentiation and flagellar pocket dynamics.
authors.affiliation: Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK.
authors.forename: Lesley S
authors.initials: LS
authors.lastname: Morrison
authors.forename: Amy
authors.initials: A
authors.lastname: Goundry
authors.forename: Marilia S
authors.initials: MS
authors.lastname: Faria
authors.forename: Laurence
authors.initials: L
authors.lastname: Tetley
authors.forename: Sylvain C
authors.initials: SC
authors.lastname: Eschenlauer
authors.forename: Gareth D
authors.initials: GD
authors.lastname: Westrop
authors.forename: Anna
authors.initials: A
authors.lastname: Dostalova
authors.forename: Petr
authors.initials: P
authors.lastname: Volf
authors.forename: Graham H
authors.initials: GH
authors.lastname: Coombs
authors.forename: Ana Paula C A
authors.initials: AP
authors.lastname: Lima
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Mottram
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005407:Flagella / Q000378:metabolism / Q000648:ultrastructure; D055786:Gene Knockout Techniques; D006790:Host-Parasite Interactions; D018320:Leishmania major / Q000235:genetics / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D017737:Macrophages, Peritoneal / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport; D053491:Proteinase Inhibitory Proteins, Secretory / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D022142:Secretory Vesicles / Q000378:metabolism / Q000648:ultrastructure; D057057:Serine Proteases / Q000737:chemistry
chemical_list: D011480:Protease Inhibitors; D053491:Proteinase Inhibitory Proteins, Secretory; D015800:Protozoan Proteins; D057057:Serine Proteases