Abstract
The intracellular protozoan parasites of the Leishmania genus are responsible for Leishmaniases, vector borne diseases with a wide range of clinical manifestations. Leishmania (L.) donovani causes visceral leishmaniasis (kala azar), the most severe of these diseases. Along their biological cycle, Leishmania parasites undergo distinct developmental transitions including metacyclogenesis and differentiation of metacyclic promastigotes (MPs) to amastigotes. Metacyclogenesis inside the phlebotomine sandfly host’s midgut converts the procyclic dividing promastigotes to non-dividing infective MPs eventually injected into the skin of mammalian hosts and phagocytosed by macrophages where the MPs are converted inside modified phagolysosomes to the intracellular amastigotes. These developmental transitions involve dramatic changes in cell size and shape and reformatting of the flagellum requiring thus membrane and cytoskeleton remodeling in which phosphoinositide (PI) signaling and metabolism must play central roles. This study reports on the LDBPK_220120.1 gene, the L. donovani ortholog of LmjF.22.0250 from L. major that encodes a phosphatase from the “Atypical Lipid Phosphatases” (ALPs) enzyme family. We confirmed the expression of the LDBPK_220120.1 gene product in both L. donovani promastigotes and axenic amastigotes and showed that it behaves in vitro as a Dual Specificity P-Tyr and monophosphorylated [PI(3)P and PI(4)P] PI phosphatase and therefore named it LdTyrPIP_22 (Leishmaniad onovani Tyrosine PI Phosphatase, gene locus at chromosome 22). By immunofluorescence confocal microscopy we localized the LdTyrPIP_22 in several intracellular sites in the cell body of L. donovani promastigotes and amastigotes and in the flagellum. A temperature and pH shift from 25°C to 37°C and from pH 7 to 5.5, induced a pronounced recruitment of LdTyrPIP_22 epitopes to the flagellar pocket and a redistribution around the nucleus. These results suggest possible role(s) for this P-Tyr/PI phosphatase in the regulation of processes initiated or upregulated by this temperature/pH shift that contribute to the developmental transition from MPs to amastigotes inside the mammalian host macrophages.
Highlights
IntroductionLeishmania parasites, a class of trypanosomatid protozoans of the kinetoplastidae family, parasitize both invertebrate (sandflies of the genus Phlebotomus or Lutzomyia) and vertebrate hosts
Leishmania parasites, a class of trypanosomatid protozoans of the kinetoplastidae family, parasitize both invertebrate and vertebrate hosts
Our interest on PI phosphatases in Leishmania spp. focused on a study identifying the Leishmania major LmjF.22.0250 gene that encodes for a dual specificity PI and P-Tyr phosphatase (Beresford et al, 2010). This protein (LM1) contains the putative P-loop motif (HCXXGKDR[TA]G) of Protein Tyrosine Phosphatases (PTPs) detected in the Mptpb triple specificity PI phosphatase from M. tuberculosis and in the LipA dual specificity P-Tyr and PI phosphatase from L. monocytogenes (Beresford et al, 2010)
Summary
Leishmania parasites, a class of trypanosomatid protozoans of the kinetoplastidae family, parasitize both invertebrate (sandflies of the genus Phlebotomus or Lutzomyia) and vertebrate hosts. When transmitted to the mammal host by the sandfly bite upon blood-feeding, Leishmania parasites are responsible for leishmaniases, a wide spectrum of diseases, which are major public health threats in endemic areas (WHO/PAHO, 2020). The few anti-leishmania drugs available to date present serious limitations. They are associated with severe side effects/toxicity or teratogenicity, high cost or emergence/spread of drugresistant parasites in the field (Ghorbani and Farhoudi, 2018). There is an urgent need to develop new specific and safe anti-parasitic compounds. In such framework, the identification of molecular determinants along the complex life cycle of these parasites should enlarge the target repertoire for designing anti-parasitic strategies
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