NDK/NME proteins: a host–pathogen interface perspective towards therapeutics

No effective vaccine is available for any parasitic disease. The treatment to those is solely dependent on chemotherapy, which is always threatened due to development of drug resistance in bugs. This warrants identification of new drug targets. Here, we discuss Nucleoside diphosphate kinases (NDKs) of pathogens that alter host's intra and extracellular environment, as novel drug targets to simultaneously tackle multiple pathogens. NDKs having diverse functions, are highly conserved among prokaryotes and eukaryotes (the mammal NDKs are called NMEs [non-metastatic enzymes]). However, NDKs and NMEs have been separately analysed in the past for their structure and functions. The role of NDKs of pathogen in modulation of inflammation, phagocytosis, apoptosis, and ROS generation in host is known. Conversely, its combined contribution in host-pathogen interaction has not been studied yet. Through the sequence and domain analysis, we found that NDKs can be classified in two groups. One group comprised NMEs 1-4 and few NDKs of select essential protozoan parasites and the bacterium Mycobacterium tuberculosis. The other group included NME7 and the other NDKs of those parasites, posing challenges in the development of drugs specifically targeting pathogen NDKs, without affecting NME7. However, common drugs targeting group 2 NDKs of pathogens can be designed, as NME7 of group 2 is expressed only in ciliated host cells. This review thus analyses comparatively for the first time the structures and functions of human NMEs and pathogen NDKs and predicts the possibilities of NDKs as drug targets. In addition, pathogen NDKs have been now provided a nomenclature in alignment with the NMEs of humans.