Single GDP-dissociation Inhibitor Protein regulates endocytic and secretory pathways in Leishmania

Abstract

The role of GDP dissociation inhibitor (GDI) protein in regulation of Rab cycle in Leishmania is not known. Here, we have cloned and characterized the functions of GDI homologue in vivo in Leishmania. Our results have shown that LdGDI:WT along with GDP removes the Rab5 from purified endosomes and inhibits the homotypic fusion between early endosomes. Whereas, LdGDI:R239A, a dominant negative mutant of GDI, under the same condition neither removes the Rab5 from endosome nor inhibits fusion. To determine the role of Ld-GDI in vivo, transgenic parasites overexpressing GFP-LdGDI:WT or GFP-LdGDI:R239A, are co-expressed with RFP-LdRab5:WT, RFP-LdRab7:WT or RFP-LdRab1:WT. Our results have shown that overexpression of GFP-LdGDI:WT extracts the RFP-LdRab5, RFP-LdRab7 or RFP-LdRab1 from their discrete endomembrane predominantly into cytosol. No change in the distribution of indicated Rabs is detected with overexpression of GFP-LdGDI:R239A. To determine the functional significance, we have used hemoglobin as an endocytic marker and gp63 as a marker for secretory pathway. We have found that overexpression of GFP-LdGDI:WT enhances the lysosomal targeting of internalized hemoglobin and the secretion of gp63 in the parasites possibly by triggering Rab cycle. This is the first demonstration of a single GDI ubiquitously regulating both endocytic and secretory pathways in Leishmania.

GTPase Sar1 regulates the trafficking and secretion of the virulence factor gp63 in Leishmania

“…Recently, we have shown that Ldgp63 is trafficked via Rab1 dependent conventional secretory pathway in Leishmania (36). Moreover, we have also shown that Leishmania has conserved trafficking pathways like higher eukaryotic cells (37)(38)(39)(40)(41)(42)(43)(44). Thus, it is tempting to speculate that Ldgp63 might exit from ER by Sar1-dependent COPII mediated process.…”

Biophysical and Amyloid Behaviour of a Recombinant Rab1 Isoform of Leishmania Donovani

“…The vesicular cargo movement is coordinated by Rab proteins, which act as global molecular switches. In Leishmania, Rab functions are vital for the leishmaniasis infection and propagation [12]. Endocytic functions of Rab5 and Rab7 [10,12] and secretory role of Rab1 [8] have been experimentally reported.…”

“…In Leishmania, Rab functions are vital for the leishmaniasis infection and propagation [12]. Endocytic functions of Rab5 and Rab7 [10,12] and secretory role of Rab1 [8] have been experimentally reported. Biophysical characteristics of a recombinant Rab5 have been described.…”

“…Molecular functions of four Rab proteins of L. donovani are experimentally described. [10][11][12]. Biophysical chemistry aspects of only a few protozoan Rabs have been explored [10].…”