Vitamin K2 Mediates Electron Transport from NADH Dehydrogenase 2 to bd-type Quinol Oxidase in Lacticaseibacillus rhamnosus CM MSU 529.

Autor: Dinarieva, T. Yu., Klimko, A. I., Cherdyntseva, T. A., Bryukhanov, A. L., Netrusov, A. I.
Zdroj: Moscow University Biological Sciences Bulletin; Sep2022, Vol. 77 Issue 3, p172-177, 6p
Abstrakt: Lacticaseibacillus rhamnosus CM MSU 529 was grown in a batch culture under intensive aeration in the presence of 38 µM hemin and 18 µM vitamin K2 as a source of menaquinone to activate respiratory metabolism. Unsupplemented aerobic culture served as a control. Supplementation of the growth medium with hemin or menaquinone alone had no significant effect on the culture growth. In respiratory conditions (hemin + K2), a biomass production was 2.86 ± 0.05 g dw cells/L for a 24-h culture; the molar growth yield coefficient YP/S after 18 h of cultivation was 25.6 ± 1.5 g dw cells/mol of glucose consumed. Both values were 27% higher compared to those for the aerobic conditions. Spectral analysis revealed the presence of cytochromes b- and d-types in membranes of L. rhamnosus CM MSU 529. The activity of the bacterial electron transport chain was investigated using polarography. Membrane preparations of cells grown aerobically in a hemin-supplemented medium intensively consumed oxygen in the presence of 1 mM NADH. The addition of 0.2 mM menaquinone to the reaction mixture was accompanied by a 4.6-fold increase in NADH oxidation rate. Enzymes presumably involved in NADH oxidation by membranes and identified using MALDI-TOF MS/MS included pyridine nucleotide-disulfide oxidoreductase (Nox-2), NADH dehydrogenase 2 (Ndh-2), and ubiquinol oxidase bd subunit I (CydA). Therefore, in NADH oxidation, 80% of electron transport from NADH to oxygen occurred via Ndh-2, menaquinone, and bd-type quinol oxidase; as little as 20% were transfered via Nox-2. The study reports experimental evidence to support an electron transport chain functioning in L. rhamnosus CM MSU 529 under aerobic cultivation in the presence of hemin and menaquinone. The NADH oxidation rates of membrane preparations of lactic acid bacteria were measured for the first time. Additionally, this is the first time when the property of exogenous menaquinone to transfer electrons from Ndh-2 to bd-type quinol oxidase was demonstrated in vitro in lactic acid bacteria. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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