Adenine aminohydrolase from Leishmania donovani. Unique enzyme in parasite purine metabolism

Jan M. Boitz, Rona Strasser, Charles U. Hartman, Armando Jardim, Buddy Ullman

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Adenine aminohydrolase (AAH) is an enzyme that is not present in mammalian cells and is found exclusively in Leishmania among the protozoan parasites that infect humans. AAH plays a paramount role in purine metabolism in this genus by steering 6-aminopurines into 6-oxypurines. Leishmania donovani AAH is 38 and 23% identical to Saccharomyces cerevisiae AAH and human adenosine deaminase enzymes, respectively, catalyzes adenine deamination to hypoxanthine with an apparent K m of 15.4 μM, and does not recognize adenosine as a substrate. Western blot analysis established that AAH is expressed in both life cycle stages of L. donovani, whereas subcellular fractionation and immunofluorescence studies confirmed that AAH is localized to the parasite cytosol. Deletion of the AAH locus in intact parasites established that AAH is not an essential gene and that Δaah cells are capable of salvaging the same range of purine nucleobases and nucleosides as wild type L. donovani. The Δaah null mutant was able to infect murine macrophages in vitro and in mice, although the parasite loads in both model systems were modestly reduced compared with wild type infections. The Δaah lesion was also introduced into a conditionally lethal Δhgprt/Δxprt mutant in which viability was dependent on pharmacologic ablation of AAH by 2′-deoxycoformycin. The Δaah/- Δhgprt/Δxprt triple knock-out no longer required 2′-deoxycoformycin for growth and was avirulent in mice with no persistence after a 4-week infection. These genetic studies underscore the paramount importance of AAH to purine salvage by L. donovani.

Original languageEnglish (US)
Pages (from-to)7626-7639
Number of pages14
JournalJournal of Biological Chemistry
Volume287
Issue number10
DOIs
StatePublished - Mar 2 2012

Fingerprint

adenine deaminase
Leishmania donovani
Metabolism
Parasites
Enzymes
Pentostatin
Salvaging
purine
Parasite Load
Purine Nucleosides
Deamination
Hypoxanthine
Macrophages
Leishmania
Essential Genes
Adenine

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Adenine aminohydrolase from Leishmania donovani. Unique enzyme in parasite purine metabolism. / Boitz, Jan M.; Strasser, Rona; Hartman, Charles U.; Jardim, Armando; Ullman, Buddy.

In: Journal of Biological Chemistry, Vol. 287, No. 10, 02.03.2012, p. 7626-7639.

Research output: Contribution to journalArticle

Boitz, Jan M. ; Strasser, Rona ; Hartman, Charles U. ; Jardim, Armando ; Ullman, Buddy. / Adenine aminohydrolase from Leishmania donovani. Unique enzyme in parasite purine metabolism. In: Journal of Biological Chemistry. 2012 ; Vol. 287, No. 10. pp. 7626-7639.
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