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An intracellular calcium store is present in Leishmania donovani glycosomes

Shreedhara Gupta1, Bikramjit Raychaudhury, Shouvik Banerjee

  • 1Department of Biological Chemistry, Infectious Diseases Group, Indian Institute of Chemical Biology, Kolkata 700032, India.

Experimental Parasitology
|March 4, 2006
PubMed

Insights

Researchers identified a fourth intracellular calcium (Ca2+) pool in Leishmania donovani, located within glycosomes. This discovery reveals a novel mechanism for calcium regulation and cellular function in this parasite.

Area of Science:

  • Parasitology
  • Cell Biology
  • Biochemistry

Background:

  • Leishmania donovani relies on precise calcium (Ca2+) regulation for cellular functions.
  • Intracellular Ca2+ pools are crucial for signaling pathways, but their full extent in Leishmania remains unclear.

Purpose of the Study:

  • To identify and characterize novel intracellular calcium (Ca2+) pools in Leishmania donovani.
  • To investigate the role of glycosomes in calcium homeostasis and uptake mechanisms.

Main Methods:

  • Permeabilization of Leishmania donovani plasma membranes with digitonin.
  • Utilizing Fura 2 for Ca2+ imaging and release studies under various inhibitory conditions (antimycin, oligomycin, vanadate, bafilomycin).
  • Isolation and functional characterization of glycosomes, including Ca2+ uptake assays and enzyme activity measurements.

Main Results:

  • A fourth intracellular Ca2+ pool was identified, distinct from previously known pools.
  • Synergistic Ca2+ release was observed upon combined mitochondrial inhibition and vanadate treatment.
  • Purified glycosomes demonstrated vanadate-insensitive Ca2+ uptake and Ca2+-ATPase activity optimal at pH 7.5.
  • Confocal laser imaging confirmed Ca2+ presence and activity within purified glycosomes.

Conclusions:

  • Leishmania donovani possesses a fourth intracellular Ca2+ pool located in glycosomes.
  • Glycosomes play a significant role in cellular calcium regulation through a vanadate-insensitive Ca2+-ATPase.
  • This newly identified glycosomal calcium pool is a potential key player in parasite cellular function.

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