TY - JOUR
T1 - Amplification and molecular cloning of the ornithine decarboxylase gene of Leishmania donovani
AU - Hanson, Sheri
AU - Adelman, John
AU - Ullman, Buddy
N1 - Copyright:
Copyright 2004 Elsevier B.V., All rights reserved.
PY - 1992/2/5
Y1 - 1992/2/5
N2 - A strain of Leishmania donovani has been described that is resistant to DL-α-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase (OD-Case) activity, and contains 15-fold greater amounts of ODCase activity and protein than the wild type strain from which it was derived (Coons, T., Hanson, S., Bitonti, A. J., McCann, P. P., and Ullman, B. (1990) Mol. Biochem. Pharmacol. 39, 77-90). From this mutant strain, another ODCase overproducing L. donovani strain, DFMO16, was generated by virtue of its ability to proliferate under even higher concentrations of DFMO. To investigate the mechanism by which DFMO-resistant cells overexpress ODCase, the leishnianial ODCase gene was isolated by hybridization to a fragment of the L. donovani ODCase gene that was generated by the polymerase chain reaction. The nucleotide sequence of a 4.5-kilobase DNA fragment encompassed an open reading frame encoding 707 amino acids (Mr = 77,350). The leishmanial protein contained an extra ∼200 amino acid NH2-terminal extension and lacked the COOH terminus of the mammalian ODCase. Northern blot analysis revealed two leishmanial ODCase transcripts of 4.8 and 6.5 kilobases, both of which were amplified 10-20-fold in the DFMO16 cells. Genomic Southern blot analysis established that the augmented amount of ODCase activity and ODCase mRNA in the DFMO16 strain could be attributed to a ∼10-20-fold amplification of the ODCase gene copy number. DFMO16 cells exhibited an unstable phenotype in that the amplification of the ODCase gene, the increased amount of ODCase transcript, the overproduction of ODCase activity, and the DFMO-resistance growth phenotype all reverted synchronously in the absence of selective pressure.
AB - A strain of Leishmania donovani has been described that is resistant to DL-α-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase (OD-Case) activity, and contains 15-fold greater amounts of ODCase activity and protein than the wild type strain from which it was derived (Coons, T., Hanson, S., Bitonti, A. J., McCann, P. P., and Ullman, B. (1990) Mol. Biochem. Pharmacol. 39, 77-90). From this mutant strain, another ODCase overproducing L. donovani strain, DFMO16, was generated by virtue of its ability to proliferate under even higher concentrations of DFMO. To investigate the mechanism by which DFMO-resistant cells overexpress ODCase, the leishnianial ODCase gene was isolated by hybridization to a fragment of the L. donovani ODCase gene that was generated by the polymerase chain reaction. The nucleotide sequence of a 4.5-kilobase DNA fragment encompassed an open reading frame encoding 707 amino acids (Mr = 77,350). The leishmanial protein contained an extra ∼200 amino acid NH2-terminal extension and lacked the COOH terminus of the mammalian ODCase. Northern blot analysis revealed two leishmanial ODCase transcripts of 4.8 and 6.5 kilobases, both of which were amplified 10-20-fold in the DFMO16 cells. Genomic Southern blot analysis established that the augmented amount of ODCase activity and ODCase mRNA in the DFMO16 strain could be attributed to a ∼10-20-fold amplification of the ODCase gene copy number. DFMO16 cells exhibited an unstable phenotype in that the amplification of the ODCase gene, the increased amount of ODCase transcript, the overproduction of ODCase activity, and the DFMO-resistance growth phenotype all reverted synchronously in the absence of selective pressure.
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M3 - Article
C2 - 1339439
AN - SCOPUS:0026803049
SN - 0021-9258
VL - 267
SP - 2350
EP - 2359
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 4
ER -