title: Role of leishmanial acidocalcisomal pyrophosphatase in the cAMP homeostasis in phagolysosome conditions required for intra-macrophage survival.
abstract: Exposure of Leishmania donovani to macrophage phagolysosome conditions (PC) (37°C and pH 5.5) led to increased intracellular cAMP and cAMP-mediated responses, which help in intra-macrophage survival pre-requisite for infectivity. In the absence of typical orthologs for G-proteins and G-protein coupled receptors, we sought to study the precise mechanisms for positive modulation of cAMP production during exposure to PC. Amongst two promastigote-stage specific membrane bound receptor adenylate cyclases (LdRAC-A and LdRAC-B), LdRAC-A appeared to function as a major cAMP generator following PC exposure. Pyrophosphate (PPi), an energy storage compound as well as a by-product of cAMP biosynthesis by adenylate cyclise, was found to be decreased following PC exposure. This may be due to microtubule and microfilament-driven translocation of acidocalcisomes near plasma membrane vicinity with concomitant increase of acidocalcisome membrane pyrophosphatase (LdV-H+PPase) and acidocalcisomal soluble pyrophosphatase (LdVSP1). Episomal over-expression and conditional silencing demonstrated regulatory role of V-H+PPase on cAMP trigger and consequent induction of resistance to macrophage-derived pro-oxidants and parasite killing. Furthermore, immunofluorescence analysis revealed possible co-localization of LdV-H+PPase and LdRAC-A during PC exposure. Collectively, these results suggest that translocation of acidocalcisome in membrane vicinity functions as a trigger for LdRAC-A-driven cAMP generation through depletion of PPi pool by LdV-H+PPase.
authors.affiliation: Department of Zoology, University of Kalyani, Kalyani, Nadia 741325, India.
authors.forename: Arunima
authors.initials: A
authors.lastname: Biswas
authors.affiliation: Centre de Rechercheen Infectiologie, Centre de Recherche du CHU de Québec, University of Laval, Quebec City, Quebec, Canada.
authors.forename: Arijit
authors.initials: A
authors.lastname: Bhattacharya
authors.affiliation: CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata 700032, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Vij
authors.affiliation: CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata 700032, India. Electronic address: pijush52@gmail.com.
authors.forename: Pijush K
authors.initials: PK
authors.lastname: Das
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000378:metabolism; D007893:Leishmania donovani / Q000166:cytology* / Q000201:enzymology*; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D010545:Peroxides / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism*; D021381:Protein Transport; D011755:Pyrophosphatases / Q000378:metabolism*; D013696:Temperature
chemical_list: D010545:Peroxides; D000242:Cyclic AMP; D011755:Pyrophosphatases; D000262:Adenylyl Cyclases
keywords: Acidocalcisomes; Adenylate cyclase; Cyclic AMP; Leishmania donovani; Pyrophosphatase