Identification of new inhibitors for alternative NADH dehydrogenase (NDH-II)

Abstract

In bacterial membranes and plant, fungus and protist mitochondria, NADH dehydrogenase (NDH-II) serves as an alternative NADH : quinone reductase, a non-proton-pumping single-subunit enzyme bound to the membrane surface. Because NDH-II is absent in mammalian mitochondria, it is a promising target for new antibiotics. However, inhibitors for NDH-II are rare and unspecific. Taking advantage of the simple organization of the respiratory chain in Gluconobacter oxydans, we carried out screening of natural compounds and identified scopafungin and gramicidin S as inhibitors for G. oxydans NDH-II. Further, we examined their effects on Mycobacterium smegmatis and Plasmodium yoelii NDH-II as model pathogen enzymes.

Apoptosis-inducing Factor (AIF) and Its Family Member Protein, AMID, Are Rotenone-sensitive NADH:Ubiquinone Oxidoreductases (NDH-2)

“…The concentrations of half-maximal inhibition (IC 50 ) were 1.34, 1.04, and 0.75 M for Ndi1, AMID, and N-terminally tagged AIF, respectively. These values are comparable with the reported values for NDH-2 enzymes and other quinone oxidoreductases (27)(28)(29)(30). These data strongly suggest that UQ is the physiological electron acceptor for AIF and AMID, as it is for Ndi1.…”

Gramicidin S and polymyxins: the revival of cationic cyclic peptide antibiotics

“…In order to identify new inhibitors for alternative respiratory enzymes (i.e., enzymes that are not present in human mitochondria), we screened the Kitasato Institute for Life Sciences Chemical Library [30] with the following enzymes: cytochrome bd quinol oxidase from Escherichia coli [31, 32], bacterial cyanide-insensitive oxidase (CIO, a variant of cytochrome bd) and a single-subunit NADH dehydrogenase (NDH-2) from the acetic acid bacterium Gluconobacter oxydans [33,34], and NDH-2 and malate: quinone oxidoreductase (MQO) from Mycobacterium smegmatis [35] and Pseudomonas aeruginosa [36]. Cytochrome bd and CIO are widely distributed among bacteria and play an important role in microaerophilic respiration and protection against oxygen stress and in the survival and adaptation of pathogenic bacteria [37][38][39].…”

“…NDH-2s were shown to be crucial for the adaptation of M. tuberculosis [39] and malaria parasites [40,41], but their specific inhibitors are rare [42]. Therefore, inhibitors of quinol oxidases [31-33, 43] and NDH-2 [34,35,40,41,44] are promising new chemotherapeutics.…”

“…From screening with G. oxydans NDH-2, we identified GS and scopafungin as potent inhibitors and found the moderate inhibitory activity with polymyxin B [34]. GS serves as a noncompetitive inhibitor for NADH oxidation and a competitive inhibitor for quinone (Q) reduction.…”

Roles of the two type II NADH dehydrogenases in the survival of Mycobacterium tuberculosis in vitro

“…Chlorpromazine, a phenothiazine used for treating Mycobacterium leprae infections, has been shown to inhibit the biochemical activity of Ndh and NdhA (Weinstein et al, 2005). Enzyme inhibitors of bacterial Ndh have recently been reported (Mogi et al, 2009;Shirude et al, 2012). However, the essentiality of ndh genes in Mtb has not been proven unequivocally.…”