InterPro domain: IPR045024

This entry represents a group of alternative NADH:quinone oxidoreductases (also known as NDH-2) that deliver electrons to the respiratory chain by oxidation of NADH and reduction of quinones but does not pump protons [ 1 ]. NDH-2 have particular relevance in yeasts like Saccharomyces cerevisiae and in several prokaryotes, whose respiratory chains are devoid of complex I, in which NDH-2 keep the balance and are the main entry point of electrons into the respiratory chains [ 2 ]. Structures of NDH-2 from the yeast Saccharomyces cerevisiae, also called Ndi1 ( 4G6H and 4G9K ), and those from bacteria, Caldalkalibacillus thermarum ( 4NWZ ) and Staphylococcus aureus ( 4XDB7 ), have been determined [ 3 ]. Interestingly, since NDH-2s are present only in bacteria and certain plant, fungal and protozoan mitochondria, but not in mammals, they have been used as an drug target for Mycoplasma tuberculosis, Plasmodium falciparum and Toxoplasma gondii [ 4 ].

1. The respiratory chain NADH dehydrogenase of Escherichia coli. Isolation of an NADH:quinone oxidoreductase from membranes and comparison with the membrane-bound NADH:dichlorophenolindophenol oxidoreductase. J Biol Chem 256, 3077-84
2. New insights into type II NAD(P)H:quinone oxidoreductases. Microbiol Mol Biol Rev 68, 603-16
3. Structural and Functional insights into the catalytic mechanism of the Type II NADH:quinone oxidoreductase family. Sci Rep 7, 42303
4. Characterization of the type 2 NADH:menaquinone oxidoreductases from Staphylococcus aureus and the bactericidal action of phenothiazines. Biochim Biophys Acta 1837, 954-63