Enzymatic Properties of the Membrane-bound NADH Oxidase System in the Aerobic Respiratory Chain of Bacillus cereus

Abstract

Membranes prepared from Bacillus cereus KCTC 3674, grown aerobically on a complex medium, oxidized NADH exclusively, whereas deamino-NADH was little oxidized. The respiratory chain-linked NADH oxidase exhibited an apparent K m value of approximately 65 µM for NADH. The maximum activity of the NADH oxidase was obtained at about pH 8.5 in the presence of 0.1 M KCl (or NaCl). Respiratory chain inhibitor 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) inhibited the activity of the NADH oxidase by about 90% at a concentration of 40 µM. Interestingly, rotenone and capsaicin inhibited the activity of the NADH oxidase by about 60% at a concentration of 40 µM and the activity was also highly sensitive to Ag + .

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.…”

Fluorescent properties of c‐type cytochromes reveal their potential role as an extracytoplasmic electron sink in Geobacter sulfurreducens

“…Anoxic cell sususpensions of the steady‐state culture were treated with capsaicin, a well‐known inhibitor of NADH dehydrogenase (Kim and Kim, 2004), to prevent further electron transfer to the cytochromes. Addition of Fe(III) citrate to the cell suspension resulted in a decrease in fluorescence, indicating that Fe(III) citrate could oxidize the cytochromes (Fig.…”

A secondary mode of action of polymyxins against Gram-negative bacteria involves the inhibition of NADH-quinone oxidoreductase activity

“…Membrane-bound NADH-quinone oxidoreductase activity was measured as previously reported 11, 29 . Briefly, bacterial membranes (3 mg/mL) were resuspended in the above phosphate buffer containing magnesium sulphate and dispensed into the wells in presence of 200 µM ubiquinone-1 (Q 1 ) and 5 mM potassium cyanide (KCN).…”

“…In general, the bacterial respiratory chain consists of three complexes with quinones and reduced nicotinamide adenine dinucleotide (NADH) acting as the carriers that shuttle electrons and protons between large protein complexes 11–15 . The exact organization of enzymes varies among different bacteria 11–13 .…”

“…The exact organization of enzymes varies among different bacteria 11–13 . In complex 1, three inner membrane respiratory enzymes of the NADH oxidase family have been identified: proton-translocating NADH-quinone (Q) oxidoreductase (NDH-1), NADH-Q oxidoreductase which lacks an energy-coupling site (NDH-2) and the sodium-translocating NADH-Q oxidoreductase 11–13, 15 .…”