Reduced nicotinamide adenine dinucleotide oxidase activity in membranes and cytoplasm of Acholeplasma laidlawii and Mycoplasma mycoides subsp. capri

Abstract

The properties of the membrane-bound reduced nicotinamide adenine dinucleotide (NADH) oxidase of Acholeplasma laidlawii were compared with those of the corresponding cytoplasmic activity of Mycoplasma mycoides subsp. capri. The striking differences in pH optima, susceptibility to inhibitors and detergents, and heat inactivation between the NADH oxidase activity, with oxygen as an electron acceptor, and the NADH oxidoreductase activity, with dichlorophenol indophenol (DCPIP) as an alternate electron acceptor, support the presence of more than one catalytic protein in both the membrane-bound and soluble enzyme systems. The detection of more than one band positive for the NADHnitroblue tetrazolium oxidoreductase reaction on electrophoresis of either the membranes of A. laidlawii or the cytoplasm of M. mycoides subsp. capri also points in the same direction. The membrane-bound enzyme system differed, however, from the soluble one because it had a lower ratio of oxidase activity to oxidoreductase activity, and because it was less susceptible to heat inactivation and more readily incorporated into reaggregated membranes. In addition, the specific activity of the membrane-bound enzyme system increased as the culture aged, whereas that of the soluble system decreased as the culture aged. It is suggested that the different location in the cell could be responsible for some of the differences between the membrane-bound NADH oxidase activity of A. laidlawii and that found in the cytoplasm of M. mycoides subsp. capri. the washed cells by osmotic lysis as described previ-827 on August 1, 2020 by guest

The mycoplasmas.

“…Unlike that in Mycoplasma and Spiroplasma species, the NADH oxidase activity in Acholeplasma species is membrane bound (226). Yet, the Acholeplasma system resembles that of the Mycoplasma in being composed of only two enzymic proteins associated with flavins (140,141,162,171). Ruling out oxidative phosphorylation as an ATP-generating system in most, if not all, parasitic mycoplasmas leaves only two proven ways of ATP generation, both based on substratelevel phosphorylation.…”

Downregulated mitochondrial transcription factor A enhances mycoplasma infection to promote the metastasis of hepatocellular carcinoma

“… 16 Mycoplasma titers were quantified as CCU per milliliter according to a previous report. When HCC cells have confluence of roughly 80%, 10 5 CCU/ml of Mycoplasma hyorhinis was added to the cells after serum starvation for 24 h. 17 The HCC cells were then cocultured with mycoplasmas for 48 h before being harvested.…”