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A novel Sucrose/H+ Symport System and an Intracellular Sucrase in Leishmania Donovani.

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Title A novel Sucrose/H+ Symport System and an Intracellular Sucrase in Leishmania Donovani.
 
Creator Singh, Arpita
Mandal, Debjani
 
Subject Infectious Diseases and Immunology
 
Description The flagellated form of pathogenic parasitic protozoa Leishmania, resides in the alimentary tract of its
sandfly vector, where sucrose serves as a major nutrient source. In this study we report the presence
of a sucrose transport system in Leishmania donovani promastigotes. The kinetics of sucrose uptake in
promastigotes are biphasic in nature with both high affinity Km (Km of �75 lM) and low affinity Km
(Km � 1.38 mM) components. By contrast the virulent amastigotes take up sucrose via a low affinity process
with a Km of 2.5 mM. The transport of sucrose into promastigotes leads to rapid intracellular acidification,
as indicated by changes in the fluorescence of the pH indicator 20,70-bis-(2-carboxyethyl)-5-(6)
Carboxyfluorescein (BCECF). In experiments with right side-out plasma membrane vesicles derived from
L. donovani promastigotes, an artificial pH gradient was able to drive the active accumulation of sucrose.
These data are consistent with the operation of a H+-sucrose symporter. The symporter was shown to be
independent of Na+ and to be insensitive to cytochalasin B, to the flavonoid phloretin and to the Na+/K+
ATPase inhibitor ouabain. However, the protonophore carbonylcyanide P- (trifluromethoxy) phenylhydrazone
(FCCP) and a number of thiol reagents caused significant inhibition of sucrose uptake. Evidence
was also obtained for the presence of a stable intracellular pool of the sucrose splitting enzyme, sucrase,
in promastigote stage parasites. The results are consistent with the hypothesis that L. donovani promastigotes
take up sucrose via a novel H+–sucrose symport system and that, on entering the cell, the
sucrose is hydrolysed to its component monosaccharides by an intracellular sucrase, thereby providing
an energy source for the parasites
 
Publisher Elsevier
 
Date 2011
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://www.eprints.iicb.res.in/1274/1/INTERNATIONAL_JOURNAL_FOR_PARASITOLOGY___41(_8)_817%2D826;2011[71].pdf
Singh, Arpita and Mandal, Debjani (2011) A novel Sucrose/H+ Symport System and an Intracellular Sucrase in Leishmania Donovani. International Journal for Parasitology, 41 (8). pp. 817-826.
 
Relation http://dx.doi.org/10.1016/j.ijpara.2011.03.004
http://www.eprints.iicb.res.in/1274/