TY - JOUR
T1 - An acid-loading chloride transport pathway in the intraerythrocytic malaria parasite, Plasmodium falciparum
AU - Henry, Roselani I.
AU - Cobbold, Simon A.
AU - Allen, Richard J.W.
AU - Khan, Asif
AU - Hayward, Rhys
AU - Lehane, Adele M.
AU - Bray, Patrick G.
AU - Howitt, Susan M.
AU - Biagini, Giancarlo A.
AU - Saliba, Kevin J.
AU - Kirk, Kiaran
PY - 2010/6/11
Y1 - 2010/6/11
N2 - The intraerythrocytic malaria parasite exerts tight control over its ionic composition. In this study, a combination of fluorescent ion indicators and 36Cl- flux measurements was used to investigate the transport of Cl- and the Cl--dependent transport of "H+-equivalents" in mature (trophozoite stage) parasites, isolated from their host erythrocytes. Removal of extracellular Cl-, resulting in an outward [Cl-] gradient, gave rise to a cytosolic alkalinization (i.e. a net efflux of H+-equivalents). This was reversed on restoration of extracellular Cl-. The flux of H +-equivalents was inhibited by 4,4′-diisothiocyanostilbene-2, 2′-disulfonic acid and, when measured in ATP-depleted parasites, showed a pronounced dependence on the pH of the parasite cytosol; the flux was low at cytosolic pH values < 7.2 but increased steeply with cytosolic pH at values > 7.2. 36Cl- influx measurements revealed the presence of a Cl- uptake mechanism with characteristics similar to those of the Cl--dependent H+-equivalent flux. The intracellular concentration of Cl- in the parasite was estimated to be ∼48 mM in situ. The data are consistent with the intraerythrocytic parasite having in its plasma membrane a 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid-sensitive transporter that, under physiological conditions, imports Cl - together with H+-equivalents, resulting in an intracellular Cl- concentration well above that which would occur if Cl- ions were distributed passively in accordance with the parasite's large, inwardly negative membrane potential.
AB - The intraerythrocytic malaria parasite exerts tight control over its ionic composition. In this study, a combination of fluorescent ion indicators and 36Cl- flux measurements was used to investigate the transport of Cl- and the Cl--dependent transport of "H+-equivalents" in mature (trophozoite stage) parasites, isolated from their host erythrocytes. Removal of extracellular Cl-, resulting in an outward [Cl-] gradient, gave rise to a cytosolic alkalinization (i.e. a net efflux of H+-equivalents). This was reversed on restoration of extracellular Cl-. The flux of H +-equivalents was inhibited by 4,4′-diisothiocyanostilbene-2, 2′-disulfonic acid and, when measured in ATP-depleted parasites, showed a pronounced dependence on the pH of the parasite cytosol; the flux was low at cytosolic pH values < 7.2 but increased steeply with cytosolic pH at values > 7.2. 36Cl- influx measurements revealed the presence of a Cl- uptake mechanism with characteristics similar to those of the Cl--dependent H+-equivalent flux. The intracellular concentration of Cl- in the parasite was estimated to be ∼48 mM in situ. The data are consistent with the intraerythrocytic parasite having in its plasma membrane a 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid-sensitive transporter that, under physiological conditions, imports Cl - together with H+-equivalents, resulting in an intracellular Cl- concentration well above that which would occur if Cl- ions were distributed passively in accordance with the parasite's large, inwardly negative membrane potential.
UR - http://www.scopus.com/inward/record.url?scp=77953301193&partnerID=8YFLogxK
U2 - 10.1074/jbc.M110.120980
DO - 10.1074/jbc.M110.120980
M3 - Article
SN - 0021-9258
VL - 285
SP - 18615
EP - 18626
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 24
ER -