Characterization of NUDIX hydrolase from Leishmania major.

Abstract

Background: NUDIX hydrolases represent a universal family of enzymes found across all domains of life that specialize in cleaving diverse organic pyrophosphates. These enzymes share a distinctive and evolutionarily conserved 23-amino acid signature sequence known as the NUDIX box domain. Functionally, NUDIX hydrolases play crucial regulatory roles in cellular metabolism, participating in diverse physiological processes including responses to both abiotic and biotic stressors. The cellular localization and enzymatic function of Nudix Hydrolase in L. major in removal of oxidatively damaged nucleotides was not studied.

Methods: Genome sequence of Leishmania major, was searched and analyzed for NUDIX motif, it revealed nine proteins had NUDIX box domain. Further bioinformatics analysis was performed to find one or more motifs in addition to Peroxisomal Targeting Sequence (PTS-1). Cellular localization of the LmjF.31.2950 (LmNH) in L. major and the complementation assay was performed using mutT defective Escherichia coli.

Results: Nine genes with NUDIX box domain were found in L. major genome. One of the gene products, encoded by LmjF.31.2950 (LmNH), had additional motifs like NADH pyrophosphatase zinc ribbon domain and a canonical peroxisomal targeting sequence type-1 (PTS-1). Expression of GFP fusion protein with C-terminally cloned LmNH, in L. major, showed the fusion protein is targeted to microbody organelles as seen by the punctuate fluorescence. Proteomic analysis of purified glycosomes from L. major showed the presence of a single peptide with complete homology to LmNH. Complementation assay in mutT defective Escherichia coli confirmed the 'anti-mutator' function of LmNH. This preliminary report indicates that LmNH may play an important role in the nucleotide metabolism in L. major glycosomes.

Conclusions: In the present study, we have successfully identified and characterized LmjF.31.2950 (LmNH), a novel NUDIX hydrolase in Leishmania major, that functions as a glycosome-targeted NADH pyrophosphatase.