The positive effect of exogenous hemin on a resistance of strict anaerobic archaeon Methanobrevibacter arboriphilus to oxidative stresses.
Methanogenic archaeon Methanobrevibacter arboriphilus (strains AZ and DH1), which is a strict anaerobic microorganism not able to synthesize heme, possessed a very high catalase activity in the presence of 20-50 μM hemin in a growth medium. We investigated the effect of various oxidative stresses (hydrogen peroxide and oxygenation) on M. arboriphilus cells grown on the standard nutrient medium supplemented with 0.1 % yeast extract, and on the same medium supplemented with hemin. It was demonstrated that 30 μM hemin had a very significant positive effect on the resistance of M. arboriphilus strains to H(2)O(2) and O(2) stresses because of 30- to 40-fold increase of heme catalase activity. Thus, hydrogen peroxide (0.6-1.2 mM) or oxygen (3-5 %) had a strong negative impact on low-catalase cultures grown in the hemin-free standard medium, whereas the presence of 30 μM hemin in the medium results in a high yield of biomass even under conditions of four times stronger H(2)O(2) and two times stronger O(2) stresses. The intracellular catalase activity reached a high level in 30-60 min after hemin was added to the nutrient medium, but the activity already increased about 5-7-fold in 6 min after hemin addition. Our experimental data suggest that exogenous hemin provides an effective antioxidative defense in representatives of the genus Methanobrevibacter, specially playing an important role in the puromycin-insensitive formation of the active heme-containing catalase from presynthesized apoenzyme and heme.
Department of Microbiology, Faculty of Biology, Lomonosov Moscow State University, Leninskie Gory 1/12, Moscow, Russia 119234. brjuchanov@mail.ru
Andrei L
AL
Brioukhanov
Alexander I
AI
Netrusov
D018533:Biomass; D002374:Catalase / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D006427:Hemin / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D041581:Methanobrevibacter / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology*; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism
D003470:Culture Media; D006427:Hemin; D006861:Hydrogen Peroxide; D002374:Catalase; D010100:Oxygen