Myristoyl-CoA:Protein N-Myristoyltransferase, an Essential Enzyme and Potential Drug Target in Kinetoplastid Parasites

Helen P Price,Malini R Menon,Chrysoula Panethymitaki,David Goulding,Paul G Mckean,Deborah F Smith

doi:10.1074/jbc.m211391200

Helen P Price, Malini R Menon + Show 4 more

Open Access

https://doi.org/10.1074/jbc.m211391200

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Abstract

Co-translational modification of eukaryotic proteins by N-myristoylation aids subcellular targeting and protein-protein interactions. The enzyme that catalyzes this process, N-myristoyltransferase (NMT), has been characterized in the kinetoplastid protozoan parasites, Leishmania and Trypanosoma brucei. In Leishmania major, the single copy NMT gene is constitutively expressed in all parasite stages as a 48.5-kDa protein that localizes to both membrane and cytoplasmic fractions. Leishmania NMT myristoylates the target acylated Leishmania protein, HASPA, when both are co-expressed in Escherichia coli. Gene targeting experiments have shown that NMT activity is essential for viability in Leishmania. In addition, overexpression of NMT causes gross changes in parasite morphology, including the subcellular accumulation of lipids, leading to cell death. This phenotype is more extreme than that observed in Saccharomyces cerevisiae, in which overexpression of NMT activity has no obvious effects on growth kinetics or cell morphology. RNA interference assays in T. brucei have confirmed that NMT is also an essential protein in both life cycle stages of this second kinetoplastid species, suggesting that this enzyme may be an appropriate target for the development of anti-parasitic agents.

Highlights

Co-translational modification of eukaryotic proteins by N-myristoylation aids subcellular targeting and protein-protein interactions
An inhibitor based on the N terminus of ADP-ribosylation factor (ARF), the major myristoylated protein detected in [3H]myristate-labeled C. neoformans, is competitive for peptide and noncompetitive for myristoyl-CoA binding [7], and a nonpeptide inhibitor based on this sequence is at least ϳ5-fold selective for C. neoformans against human NMT [8]
Gel mobility assays indicate that a single dose of 200 ␮M is sufficient to produce ϳ50% reduction in the myristoylation of C. albicans ARF, which is consistent with fungistatic activity [9]

Summary

Introduction

Co-translational modification of eukaryotic proteins by N-myristoylation aids subcellular targeting and protein-protein interactions. In Leishmania major, the single copy NMT gene is constitutively expressed in all parasite stages as a 48.5-kDa protein that localizes to both membrane and cytoplasmic fractions.

Results

Conclusion