Molecular analysis of antioxidant genes in the extremohalophile marine bacterium Exiguobacterium sp. CNU020.
Exiguobacterium sp. CNU020, an alkaliphile and extremohalophile bacterium, is resistant to 20 mM H(2)O(2), a concentration that is lethal to most bacteria. Representative antioxidant genes of catalase and superoxide dismutase (SOD), obtained by PCR amplification of the genomic DNA, were characterized: the 252-bp catalase gene shared 77% similarity in the deduced amino acid sequence to that of E. oxidotolerans T-2-2(T). The 420-bp SOD gene had the closest similarity (94.3%) to the manganese-SOD of E. sibiricum 255-15. Through activity-staining analysis, stain CNU020 had at least four catalase isoforms: C1, C2, C3 and C4. Expression of each catalase isoform was dependent on the growth phase and oxidants but two catalases (C3 and C4) were always induced and expressed at a similar rate, indicating that they were constitutively expressed. RT-PCR-based expression analysis at the transcriptional level suggested that the catalase gene is strongly expressed in response to 2 mM H(2)O(2), 0.2 mM Paraquat and 0.2 mM menadione. However, the SOD gene exhibited no observable expression pattern with 2 mM H(2)O(2) despite its strong expression when exposed to Paraquat and menadione.
Lee
Dong-Heon
DH
Department of Environmental Education, Sunchon National University, Sunchon, 540-742, Korea.
Oh
Kye-Heon
KH
Kahng
Hyung-Yeel
HY
D000900:Anti-Bacterial Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000975:Antioxidants / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000235:genetics*; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D016877:Oxidants / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010269:Paraquat / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D024483:Vitamin K 3 / Q000378:metabolism
D000900:Anti-Bacterial Agents; D000975:Antioxidants; D001426:Bacterial Proteins; D016877:Oxidants; D024483:Vitamin K 3; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D010269:Paraquat