Modulation of Leishmania major aquaglyceroporin activity by a mitogen‐activated protein kinase

Abstract

SummaryLeishmania major aquaglyceroporin (LmjAQP1) adventitiously facilitates the uptake of antimonite [Sb(III)], an active form of Pentostam® or Glucantime®, which are the first line of defence against all forms of leishmaniasis. The present paper shows that LmjAQP1 activity is modulated by the mitogenactivated protein kinase, LmjMPK2. Leishmania parasites coexpressing LmjAQP1 and LmjMPK2 show increased Sb(III) uptake and increased Sb(III) sensitivity. When subjected to a hypo-osmotic stress, these cells show faster volume recovery than cells expressing LmjAQP1 alone. LmjAQP1 is phosphorylated in vivo at Thr-197 and this phosphorylation requires LmjMPK2 activity. Lys-42 of LmjMPK2 is critical for its kinase activity. Cells expressing altered T197A LmjAQP1 or K42A LmjMPK2 showed decreased Sb(III) influx and a slower volume recovery than cells expressing wild-type proteins. Phosphorylation of LmjAQP1 led to a decrease in its turnover rate affecting LmjAQP1 activity. Although LmjAQP1 is localized to the flagellum of promastigotes, upon phosphorylation, it is relocalized to the entire surface of the parasite. Leishmania mexicana promastigotes with an MPK2 deletion showed reduced Sb(III) uptake and slower volume recovery than wild-type cells. This is the first report where a parasite aquaglyceroporin activity is post-translationally modulated by a mitogen-activated protein kinase.

KHARON1 Mediates Flagellar Targeting of a Glucose Transporter in Leishmania mexicana and Is Critical for Viability of Infectious Intracellular Amastigotes

“…Indeed, a recent study shows that phosphorylation of LmjAQP1 is sufficient to undo its FM membrane specificity and redistributes this protein to the PPM (36). However, we cannot exclude the possibility that KH1 may be an adaptor for a subset of FM proteins, including LmxGT1, which links them to a core FM targeting machinery.…”

MAPK1 of Leishmania donovani Modulates Antimony Susceptibility by Downregulating P-Glycoprotein Efflux Pumps

“…LmjMAPK2 phosphorylates LmjAQP1 at Thr-197, which is required for its pump activity. Inhibition of AQP1 phosphorylation results in reduced influx of Sb(III), slower volume recovery of cells, and, hence, increased drug resistance (26). In another study from our laboratory, MAPK1 of L. donovani was demonstrated to be downregulated in antimony-resistant clinical isolates, and its overexpression led to an increase in parasite susceptibility to antimony by 2-fold (13).…”

“…Phosphorylation of Lmj-AQP1 at Thr-197 is required for its pump activity, and Lmj-MAPK2 activity is responsible for it. Inhibition of AQP1 phosphorylation results in reduced influx of Sb(III), slower volume recovery of cells, and, hence, increased drug resistance (26).…”

Silver and Nitrate Oppositely Modulate Antimony Susceptibility through Aquaglyceroporin 1 in Leishmania (Viannia) Species

“…Since LbAQP1 is harbored on polyploid chromosome 31 (36), it was thought to be essential for Leishmania spp. (37). However, we have recently identified an Sb-resistant L. guyanensis strain from which a locus containing LgAQP1 was deleted during an in vitro stepwise drug selection process (16).…”