Pentamidine Is Not a Permeant but a Nanomolar Inhibitor of the Trypanosoma brucei Aquaglyceroporin-2

Jie Song, Nicola Baker, Monja Rothert, Björn Henke, Laura Jeacock, David Horn, Eric Beitz (Lead / Corresponding author)

Research output: Contribution to journalArticle

28 Citations (Scopus)
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Abstract

The chemotherapeutic arsenal against human African trypanosomiasis, sleeping sickness, is limited and can cause severe, often fatal, side effects. One of the classic and most widely used drugs is pentamidine, an aromatic diamidine compound introduced in the 1940s. Recently, a genome-wide loss-of-function screen and a subsequently generated trypanosome knockout strain revealed a specific aquaglyceroporin, TbAQP2, to be required for high-affinity uptake of pentamidine. Yet, the underlying mechanism remained unclear. Here, we show that TbAQP2 is not a direct transporter for the di-basic, positively charged pentamidine. Even though one of the two common cation filters of aquaglyceroporins, i.e. the aromatic/arginine selectivity filter, is unconventional in TbAQP2, positively charged compounds are still excluded from passing the channel. We found, instead, that the unique selectivity filter layout renders pentamidine a nanomolar inhibitor of TbAQP2 glycerol permeability. Full, non-covalent inhibition of an aqua(glycero)porin in the nanomolar range has not been achieved before. The remarkable affinity derives from an electrostatic interaction with Asp265 and shielding from water as shown by structure-function evaluation and point mutation of Asp265. Exchange of the preceding Leu264 to arginine abolished pentamidine-binding and parasites expressing this mutant were pentamidine-resistant. Our results indicate that TbAQP2 is a high-affinity receptor for pentamidine. Taken together with localization of TbAQP2 in the flagellar pocket of bloodstream trypanosomes, we propose that pentamidine uptake is by endocytosis.

Original languageEnglish
Article numbere1005436
Number of pages14
JournalPLoS Pathogens
Volume12
Issue number2
DOIs
Publication statusPublished - 1 Feb 2016

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Aquaglyceroporins
Pentamidine
Trypanosoma brucei brucei
African Trypanosomiasis
Trypanosomiasis
Arginine
Porins
Endocytosis
Static Electricity
Point Mutation
Glycerol
Cations
Permeability
Parasites

Cite this

Song, Jie ; Baker, Nicola ; Rothert, Monja ; Henke, Björn ; Jeacock, Laura ; Horn, David ; Beitz, Eric. / Pentamidine Is Not a Permeant but a Nanomolar Inhibitor of the Trypanosoma brucei Aquaglyceroporin-2. In: PLoS Pathogens. 2016 ; Vol. 12, No. 2.
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Pentamidine Is Not a Permeant but a Nanomolar Inhibitor of the Trypanosoma brucei Aquaglyceroporin-2. / Song, Jie; Baker, Nicola; Rothert, Monja; Henke, Björn; Jeacock, Laura; Horn, David; Beitz, Eric (Lead / Corresponding author).

In: PLoS Pathogens, Vol. 12, No. 2, e1005436, 01.02.2016.

Research output: Contribution to journalArticle

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