Uptake and metabolism of S-adenosyl-l-methionine by Leishmania mexicana and Leishmania braziliensis promastigotes

Avila, JoséL.; Polegre, María Argelia

doi:10.1016/0166-6851(93)90096-g

Cited by 18 publications

(17 citation statements)

References 25 publications

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“…Biochemical evidence was later obtained that demon- strated both the capacity of Leishmania to accumulate AdoMet (40) and that AdoMet and SNF shared the same uptake system (21). Our study now identifies the high affinity AdoMet transporter in Leishmania as AdoMetT1, a membrane protein in the FBT family.…”

Section: Discussionmentioning

confidence: 51%

High Affinity S-Adenosylmethionine Plasma Membrane Transporter of Leishmania Is a Member of the Folate Biopterin Transporter (FBT) Family

Dridi¹,

Ouameur²,

Ouellette

2010

Journal of Biological Chemistry

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S-Adenosylmethionine (AdoMet) is an important methyl group donor that plays a central role in many essential biochemical processes. The parasite Leishmania can both synthesize and transport AdoMet. Leishmania cells resistant to the antifolate methotrexate due to a rearrangement in folate biopterin transporter (FBT) genes were cross-resistant to sinefungin, an AdoMet analogue. FBT gene rearrangements were also observed in Leishmania major cells selected for sinefungin resistance. One of the rearranged FBT genes corresponded to the main AdoMet transporter (AdoMetT1) of Leishmania as determined by gene transfection and gene inactivation experiments. AdoMetT1 was determined to be a high affinity plasma membrane transporter expressed constitutively throughout the growth phases of the parasite. Leishmania cells selected for resistance or naturally insensitive to sinefungin had lower expression of AdoMetT1. A new function in one carbon metabolism, also a pathway of interest for chemotherapeutic interventions, is described for a novel class of membrane proteins found in diverse organisms.The parasite Leishmania is distributed globally and causes a variety of clinical symptoms ranging from self-healing cutaneous lesions to visceral infections that are usually fatal if left untreated (1, 2). Current first-line chemotherapy against leishmaniasis relies on a rather limited arsenal of drugs, including pentavalent antimonials, liposomal amphotericin B, or miltefosine (2). These drugs are associated with side effects, high costs, and drug resistance, and therefore, the search for new drugs and targets to control this parasite is warranted (3, 4).S-Adenosylmethionine (AdoMet or SAM) 5 is an important biological sulfonium compound recognized as the universal methyl donor for methylation of lipids, proteins, nucleic acids, and xenobiotics in living cells (5). AdoMet is also a donor of propylamine groups for the synthesis of polyamines and participates in the reverse trans-sulfuration pathway where AdoMet is converted into cysteine and glutathione and in Leishmania in the spermidine-glutathione conjugate trypanothione (6, 7). AdoMet is also used as a source of methylene groups, amino groups, and ribosyl groups in the synthesis of fatty acids, biotin, and the modified nucleoside epoxyqueusine of tRNAs (reviewed in Ref. 8).Most cells are capable of synthesizing AdoMet from L-methionine and ATP, in a process requiring the enzyme methionine adenosyltransferase (MAT). The gene coding for this enzyme is present in most sequenced organisms (reviewed in Ref. 9). However, in some Rickettsia strains, the MAT gene is inactivated by a mutation (10), and in the fungus Pneumocystis carinii, no MAT activity has been detected (11). These organisms have the rare distinction of meeting their AdoMet needs by importing it (12). The Rickettsia transporter is part of the drug/ metabolite transporter superfamily (10), and the identity of the Pneumocystis transporter is not known. Transport of AdoMet across the plasma membrane does not occur to a signifi...

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Section: Discussionmentioning

confidence: 51%

High Affinity S-Adenosylmethionine Plasma Membrane Transporter of Leishmania Is a Member of the Folate Biopterin Transporter (FBT) Family

Dridi¹,

Ouameur²,

Ouellette

2010

Journal of Biological Chemistry

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“…The most extensive information available on AdoMet transport by a pathogen is for Leishmania , an intracellular parasite of mammals. Similar to Pneumocystis , this protozoan actively imports AdoMet in an energy dependent fashion in that reduced temperature, sulfhydryl reagents, metabolic inhibitors and ATPase inhibitors block transport [20,21]. Transport does not require the presence of sodium ions but does require both pH and ΔΨ gradients.…”

Section: Adomet Transportmentioning

confidence: 99%

“…Transport does not require the presence of sodium ions but does require both pH and ΔΨ gradients. Various transporter K m values have been reported: 0.125 μM for both Leishmania mexicana and Leishmania braziliensis [20] and 1.18 and 0.89 μM for two strains of Leishmania donovani [22]. Sinefungin inhibits AdoMet transport in a competitive fashion [22] indicating that they use a common transporter.…”

Section: Adomet Transportmentioning

confidence: 99%

S-Adenosylmethionine and Pneumocystis

Merali

Clarkson

2004

FEMS Microbiology Letters

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Pneumocystis is a parasitic fungus causing pneumonia in immunosuppressed mammals and S‐adenosylmethionine a key intermediary metabolite for all cells. Other than a species of Rickettsia bacteria and an aberrant strain of the protozoan Amoeba proteus, Pneumocystis is the only cell known unable to synthesize AdoMet; it must extract this key compound from its host. This was discovered using a culture system and confirmed by observing depletion of AdoMet in the plasma of infected animals. Depletion also occurs in patients with Pneumocystis pneumonia (PcP), a phenomenon suggested as a basis for a method for diagnosis and evaluation of response to therapy. Preliminary data indicate that deliberate reduction of host lung AdoMet by nicotine treatment is therapeutic in the rat model of Pneumocystis pneumonia.

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“…Incorporation of [methyl-14C]AdoMet was also inhibitable by 2 nM sinefungin, a potent protein methylase I1 inhibitor in trypanosomes [26], indicating that a substantial portion of methylation activity was attributable to carboxylmethylation. In keeping with the overall uncontrolled rate of AdoMet synthesis, trypanosomes treated with sinefungin or cycloheximide accumulate AdoMet from [35S]methionine at a rate 2 This fraction is the combined organic extractions of the lysate with ch1oroform:methanol. and chloroform:methanol:H,O, dried and resuspended in ch1oroform:methanol as described in Materials and Methods.…”

Section: Discussionmentioning

confidence: 99%

Rapid Methylation of Cell Proteins and Lipids in Trypanosoma brucei

Goldberg

Yarlett

Rattendi

et al. 1997

J Eukaryotic Microbiology

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The fate of the [methyl-14C] group of S-adenosylmethionine (AdoMet) in bloodstream forms of Trypanosoma brucei brucei, was studied. Trypanosomes were incubated with either [methyl-14C]methionine, [U-14C]methionine, S-[methyl-14C]AdoMet or [33S]methionine and incorporation into the total TCA precipitable fractions was followed. Incorporation of label into protein through methylation was estimated by comparing molar incorporation of [methyl-14C] and [U-14C]methionine to [35S]methionine. After 4-h incubation with [U-14C]methionine, [methyl-14C]methionine or [35S]methionine, cells incorporated label at mean rates of 2,880 pmol, 1,305 pmol and 296 pmol per mg total cellular protein, respectively. Cells incubated with [U-14C] or [methyl-14C]methionine in the presence of cycloheximide (50 micrograms/ml) for four hours incorporated label eight- and twofold more rapidly, respectively, than cells incubated with [35S]methionine and cycloheximide. [Methyl-14C] and [U-14C]methionine incorporation were > 85% decreased by co-incubation with unlabeled AdoMet (1 mM). The level of protein methylation remaining after 4-h treatment with cycloheximide was also inhibited with unlabeled AdoMet. The acid precipitable label from [U-14C]methionine incorporation was not appreciably hydrolyzed by DNAse or RNAse treatment but was 95% solubilized by proteinase K. [U-14C]methionine incorporated into the TCA precipitable fraction was susceptible to alkaline borate treatment, indicating that much of this label (55%) was incorporated as carboxymethyl groups. The rate of total lipid methylation was found to be 1.5 times that of protein methylation by incubating cells with [U-14C]methionine for six hours and differential extraction of the TCA lysate. These studies show T. b. brucei maintains rapid lipid and protein methylation, confirming previous studies demonstrating rapid conversion of methionine to AdoMet and subsequent production of post-methylation products of AdoMet in African trypanosomes.

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Uptake and metabolism of S-adenosyl-l-methionine by Leishmania mexicana and Leishmania braziliensis promastigotes

Cited by 18 publications

References 25 publications

High Affinity S-Adenosylmethionine Plasma Membrane Transporter of Leishmania Is a Member of the Folate Biopterin Transporter (FBT) Family

High Affinity S-Adenosylmethionine Plasma Membrane Transporter of Leishmania Is a Member of the Folate Biopterin Transporter (FBT) Family

S-Adenosylmethionine and Pneumocystis

Rapid Methylation of Cell Proteins and Lipids in Trypanosoma brucei

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