The effect of buthionine sulfoximine on the growth ofLeishmania donovaniin culture

Abstract

Changes in composition of the principal low molecular mass thiols of Leishmania donovani were monitored during the transformation of promastigotes, first to stationary phase metacyclic forms and then to amastigotes. No consistent variation in the thiol composition of the parasite which could account for the known increase in resistance of metacyclic and amastigote lifecycle forms to oxidant stress could be established. Amastigotes cultivated at 37 degrees C also produced ovothiol A, as judged by incorporation of radiolabel from [3-methyl]methionine and [14C]histidine, and the incorporation of radiolabel from [35S]cysteine into ovothiol A represented about 10-15% of the total label recovered in ovothiol A, glutathione and trypanothione. Amastigotes were less susceptible than promastigotes to the effects of the redox cyclers paraquat and menadione and grew in culture in the presence of up to 20 mM buthionine sulfoximine, which completely blocked the synthesis of glutathione and its spermidine conjugates. Glutathione and trypanothione biosynthesis is, therefore, not necessary for the replication of L. donovani amastigotes in culture. Inhibition of the formation of glutathione and trypanothione did not result in an upregulation of ovothiol A production.

Trypanothione as a Target in the Design of Antitrypanosomal and Antileishmanial Agents

“…The first and ratelimiting step is the synthesis of γ-glutamylcysteine However L.donovani amastigotes which show an increased resistance against oxidative stress are less susceptible to buthionine sulphoximine [45]. This sulphoximine is the most active and most selective (vs. glutamine synthetase) among a series of Salkyl homocysteine sulphoximines.…”

The ChaC family of γ-glutamyl cyclotransferases is required for Leishmania to switch to a slow growth state and for long-term survival of the parasite

“…We report here a beneficial role of LmChaC2 proteins in promastigote stage of parasites; LmChaC2-dependent degradation of GSH to Cys, Glu, and Gly may be required for survival in stationary phase culture. Earlier work reports no significant change in the total intracellular thiol concentration during various logarithmic growth phases, but a 6-fold decrease in thiol level is observed as the parasites enter the stationary phase ( 43 ). Similarly, the T(SH) 2 concentration (1–2 mM) remains unaltered during the different logarithmic growth phases of the insect stages of Trypanosoma cruzi , L. major , and Leishmania donovani but decreases rapidly during the stationary phase culture ( 28 ).…”

Identification of 1,2,3-triazolium salt-based inhibitors of Leishmania infantum trypanothione disulfide reductase with enhanced antileishmanial potency in cellulo and increased selectivity

“…In order to characterize the observed H 2 O 2 -induced de novo thiol synthesis, we performed the same experiments on parasites previously exposed to D,L-buthionine-(S,R)-sulfoximine (BSO) [56]. BSO is a well-known inhibitor of γ-glutamylcysteine synthetase, the rate-limiting enzyme of GSH synthesis [57], although it has also been described as an inhibitor of T. cruzi trypanothione synthetase [58].…”