title: Toxoplasma gondii Hsp20 is a stripe-arranged chaperone-like protein associated with the outer leaflet of the inner membrane complex.
abstract: BACKGROUND
  Toxoplasma gondii is among the most successful parasites, with nearly half of the human population chronically infected. T. gondii has five sHsps [small Hsps (heat-shock proteins)] located in different subcellular compartments. Among them, Hsp20 showed to be localized at the periphery of the parasite body. sHsps are widespread, constituting the most poorly conserved family of molecular chaperones. The presence of sHsps in membrane structures is unusual.
  
  
  RESULTS
  The localization of Hsp20 was further analysed using high-resolution fluorescent light microscopy as well as electron microscopy, which revealed that Hsp20 is associated with the outer surface of the IMC (inner membrane complex), in a set of discontinuous stripes following the same spiralling trajectories as the subpellicular microtubules. The detergent extraction profile of Hsp20 was similar to that of GAP45 [45 kDa GAP (gliding-associated protein)], a glideosome protein associated with the IMC, but was different from that of IMC1 protein. Although we were unable to detect interacting protein partners of Hsp20 either in normal or stressed tachyzoites, an interaction of Hsp20 with phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate phospholipids could be observed.
  
  
  CONCLUSIONS
  Hsp20 was shown to be associated with a specialized membranous structure of the parasite, the IMC. This discontinuous striped-arrangement is unique in T. gondii, indicating that the topology of the outer leaflet of the IMC is not homogeneous.
authors.affiliation: Laboratorio de Parasitologia Molecular, Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, Chascomús, Argentina.
authors.forename: Natalia
authors.initials: N
authors.lastname: de Miguel
authors.forename: Maryse
authors.initials: M
authors.lastname: Lebrun
authors.forename: Aoife
authors.initials: A
authors.lastname: Heaslip
authors.forename: Ke
authors.initials: K
authors.lastname: Hu
authors.forename: Con J
authors.initials: CJ
authors.lastname: Beckers
authors.forename: Mariana
authors.initials: M
authors.lastname: Matrajt
authors.forename: Jean F
authors.initials: JF
authors.lastname: Dubremetz
authors.forename: Sergio O
authors.initials: SO
authors.lastname: Angel
mesh_terms: D000818:Animals; D022082:Cellular Structures / Q000737:chemistry / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D018274:Electroporation; D005455:Fluorescent Antibody Technique; D050886:HSP20 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D008566:Membranes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D010743:Phospholipids / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D014122:Toxoplasma / Q000166:cytology / Q000235:genetics / Q000378:metabolism
chemical_list: D050886:HSP20 Heat-Shock Proteins; D018832:Molecular Chaperones; D010743:Phospholipids; D015800:Protozoan Proteins