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Oxygen reduction in the cells of marine strict anaerobic bacteria – hyperthermophile Thermotoga maritima and psychrophile Desulfofrigus spтезисы доклада Электронная публикация
- Авторы: Brioukhanov A., Brasseur G., Pieulle L., Pimenov N., Netrusov A., Dolla A.
- Сборник: Book of Abstracts of 10th International Congress on Extremophiles EXTREMOPHILES 2014
- Тезисы
- Год издания: 2014
- Место издания: Saint Petersburg
- Первая страница: 215
- Последняя страница: 216
- Аннотация: The hyperthermophile Thermotoga maritima, although strictly anaerobic bacterium, is not only able to grow in the presence of a low amount of oxygen in the gas phase (up to 0.5% v/v) but could also consume it. T. maritima consumes O2 via a three-partner chain involving an NADH oxidoreductase (NRO), a rubredoxin (Rd) and a flavo-diiron protein (FprA). In vitro experiments demonstrated that the NADH-dependent O2 consumption rate was 881.9 mol O2 min-1 per mol of FprA at 37°C and that water was the main end product of the reaction. Phylogenetic analyses suggest that the genes coding for the aforementioned three proteins were acquired by an ancestor of Thermotogales from an ancestor of Thermococcales via a single gene transfer. This event likely also involved two ROS scavenging enzymes (neelaredoxin and rubrerythrin) that are encoded by genes clustered with those coding for FprA, NRO and Rd in the ancestor of Thermococcales. Such genomic organization would have provided the ancestor of Thermotogales with a complete set of enzymes dedicated to antioxidative defence. A psychrophilic asporogenous sulfate-reducing bacterium, isolated recently from the oxygenated sub-surface water layer (310 μM of O2, depth 30 m) of the Black Sea and belonged to the genus Desulfofrigus according to the results of 16S rRNA sequencing, could also consume O2. With the use of degenerated primers the genes coding for rubredoxin: oxygen oxidoreductase (ROO), cytochrome bd ubiquinol oxidase subunit I (CydA) and cytochrome c oxidase subunit I (CoxI) were detected in the genome of Desulfofrigus sp. as well as dfx and rbr genes coding for desulfoferrodoxin and rubrerythrin. From the spectra, an amount of 0.15 nmol cytochrome d and 0.55 nmol cytochrome c per mg total protein was found. In the absence of any exogenous substrate, an oxygen consumption rate of 15 nmol O2 min-1 per mg total protein was found in Desulfofrigus sp. washed cells; the same rate was with NADH and lactate as electron donors but pyruvate was the more efficient substrate for the O2 consumption increasing the rate up to 19 nmol O2 min-1 per mg total protein. The consumption rate of 91 nmol O2 min-1 per mg total protein was found in a membrane fraction of Desulfofrigus sp. in the presence of menadiol, an analog of menaquinol which are found in anaerobic bacteria. Thus, we suppose that oxygen reduction chain together with ROS scavenging enzymes plays a major role in a relative O2 tolerance of Thermotoga maritima and Desulfofrigus sp. allowing these marine strict anaerobic bacteria to cope with fluctuating oxidative conditions that exist in water column in situ.
- Добавил в систему: Брюханов Андрей Леонидович