title: Characterization of monofunctional catalase KatA from radioresistant bacterium Deinococcus radiodurans.
abstract: Catalase plays a key role in protecting cells against toxic reactive oxygen species. Here we report on the cloning, purification and characterization of a catalase (KatA, DR1998) from the extremely radioresistant bacterium Deinococcus radiodurans. The size of purified D. radiodurans KatA monomer was 65 kDa while gel filtration revealed that the size of the enzyme was 240 kDa, suggesting that KatA formed a homotetramer in solution. Purified KatA displayed a final specific activity of 68,800 U/mg of protein. The catalase activity of KatA was inhibited by sodium azide, sodium cyanide and 3-amino-1,2,4-triazole. The absorption spectrum of KatA exhibited a Soret band at 408 nm. The position of the spectral peak remained unchanged following reduction of KatA with dithionite. No peroxidase activity was found for KatA. These results demonstrate that D. radiodurans KatA is a typical monofunctional heme-containing catalase. The stability of KatA with respect to H2O2 stress was superior to that of commercially available Aspergillus niger and bovine liver catalases. The relative abundance of KatA in cells in addition to the H2O2 resistance property may play a role in the survival strategy of D. radiodurans against oxidative damage.
authors.affiliation: Department of Biofunctional Chemistry, Graduate School of Natural Science and Technology, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Issei
authors.initials: I
authors.lastname: Kobayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Tamura
authors.forename: Haitham
authors.initials: H
authors.lastname: Sghaier
authors.forename: Issay
authors.initials: I
authors.lastname: Narumi
authors.forename: Shotaro
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Koichi
authors.initials: K
authors.lastname: Umeda
authors.forename: Kenji
authors.initials: K
authors.lastname: Inagaki
mesh_terms: D000595:Amino Acid Sequence; D002374:Catalase / Q000737:chemistry*; D002850:Chromatography, Gel; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry; D034301:Deinococcus / Q000201:enzymology*; D004926:Escherichia coli / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011506:Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
chemical_list: D004269:DNA, Bacterial; D011506:Proteins; D006861:Hydrogen Peroxide; D002374:Catalase