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Antimicrobial Agents and Chemotherapy, February 2007, p. 438-445, Vol. 51, No. 2
0066-4804/07/$08.00+0     doi:10.1128/AAC.01193-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Leishmania donovani Polyamine Biosynthetic Enzyme Overproducers as Tools To Investigate the Mode of Action of Cytotoxic Polyamine Analogs{triangledown}

Sigrid C. Roberts,1 Yuqui Jiang,1,{dagger} Judith Gasteier,1,{ddagger} Benjamin Frydman,1,§ Laurence J. Marton,2 Olle Heby,3 and Buddy Ullman1*

Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239-3098,1 Cellgate Inc., Redwood City, California 94065-1517,2 Department of Molecular Biology, Umea University, Umea SE-901 87, Sweden3

Received 22 September 2006/ Returned for modification 24 October 2006/ Accepted 5 November 2006

A number of anticancer and antiparasitic drugs are postulated to target the polyamine biosynthetic pathway and polyamine function, but the exact mode of action of these compounds is still being elucidated. To establish whether polyamine analogs specifically target enzymes of the polyamine pathway, a model was developed using strains of the protozoan parasite Leishmania donovani that overproduce each of the polyamine biosynthetic enzymes. Promastigotes overexpressing episomal constructs encoding ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (ADOMETDC), or spermidine synthase (SPDSYN) revealed robust overproduction of the corresponding polyamine biosynthetic enzyme. Polyamine pools, however, were either unchanged or only marginally affected, implying that regulatory mechanisms must exist. The ODC, ADOMETDC, and SPDSYN overproducer strains exhibited a high level of resistance to difluoromethylornithine, 5'-{[(Z)-4-amino-2-butenyl]methylamino}-5'-deoxyadenosine, and n-butylamine, respectively, confirming previous observations that these agents specifically target polyamine enzymes. Conversely, augmented levels of polyamine biosynthetic enzymes did not affect the sensitivity of L. donovani promastigotes to pentamidine, berenil, and mitoguazone, drugs that were postulated to target the polyamine pathway, implying alternative and/or additional targets for these agents. The sensitivities of wild-type and overproducing parasites to a variety of polyamine analogs were also tested. The polyamine enzyme-overproducing lines offer a rapid cell-based screen for assessing whether synthetic polyamine analogs exert their mechanism of action predominantly on the polyamine biosynthetic pathway in L. donovani. Furthermore, the drug resistance engendered by the amplification of target genes and the overproduction of the encoded protein offers a general strategy for evaluating and developing therapeutic agents that target specific proteins in Leishmania.

* Corresponding author. Mailing address: Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, OR 97239-3098. Phone: (503) 494-2546. Fax: (503) 494-8393. E-mail: ullmanb{at}ohsu.edu.

{triangledown} Published ahead of print on 20 November 2006.

{dagger} Present address: Corixa Corporation, 1124 Columbia St., Seattle, WA 98104.

{ddagger} Present address: Abbott GmbH & Co. KG, Diagnostics Division, Max-Planck-Ring 2, D-65205 Wiesbaden-Delkenheim, Germany.

§ Deceased.

Antimicrobial Agents and Chemotherapy, February 2007, p. 438-445, Vol. 51, No. 2
0066-4804/07/$08.00+0     doi:10.1128/AAC.01193-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Boitz, J. M., Yates, P. A., Kline, C., Gaur, U., Wilson, M. E., Ullman, B., Roberts, S. C. (2009). Leishmania donovani Ornithine Decarboxylase Is Indispensable for Parasite Survival in the Mammalian Host. Infect. Immun. 77: 756-763 [Abstract] [Full Text]  


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