Effect of superoxide and superoxide dismutase on lignin peroxidase-catalyzed veratryl alcohol oxidation.
ABSTRACT We have shown that superoxide (O2.-) is produced during the oxidation of veratryl alcohol by lignin peroxidase (LiP) by the reaction of the veratryl alcohol cation radical with hydrogen peroxide (D. B. Barr, M. M. Shah, and S. D. Aust, 1993, J. Biol. Chem. 268, 241-244). Compound III, an inactive form of peroxidases can be formed by reaction of the ferric enzyme with O2.-. We therefore studied the effects of O2.- and superoxide dismutase (SOD) on the veratryl alcohol oxidase activity of LiP. SOD enhanced the rate of veratryl alcohol oxidation by LiP and veratryl alcohol oxidation was inhibited by the addition of KO2. Upon the addition of KO2, activity was also preceded by a lag period. Under steady-state turnover conditions (i.e., for veratryl alcohol oxidation), the addition of KO2 resulted in the formation of LiP compound III. Compound II of LiP was observed following a time period that correlated with the lag prior to veratryl aldehyde formation. The extent of the lag preceding veratryl aldehyde formation increased with increasing concentrations of KO2 and decreased with increasing concentrations of veratryl alcohol. It was postulated that during the lag period the veratryl alcohol cation radical reacted with compound III to regenerate the native enzyme. In this process the veratryl alcohol cation radical was reduced to veratryl alcohol, and thus, no veratryl aldehyde was detected during the lag period.
Article: Possible involvement of an extracellular superoxide dismutase (SodA) as a radical scavenger in poly(cis-1,4-isoprene) degradation.[show abstract] [hide abstract]
ABSTRACT: Gordonia westfalica Kb1 and Gordonia polyisoprenivorans VH2 induce the formation of an extracellular superoxide dismutase (SOD) during poly(cis-1,4-isoprene) degradation. To investigate the function of this enzyme in G. polyisoprenivorans VH2, the sodA gene was disrupted. The mutants exhibited reduced growth in liquid mineral salt media containing poly(cis-1,4-isoprene) as the sole carbon and energy source, and no SOD activity was detectable in the supernatants of the cultures. Growth experiments revealed that SodA activity is required for optimal growth on poly(cis-1,4-isoprene), whereas this enzyme has no effect on aerobic growth in the presence of water-soluble substrates like succinate, acetate, and propionate. This was detected by activity staining, and proof of expression was by antibody detection of SOD. When SodA from G. westfalica Kb1 was heterologously expressed in the sodA sodB double mutant Escherichia coli QC779, the recombinant mutant exhibited increased resistance to paraquat, thereby indicating the functionality of the G. westfalica Kb1 SodA and indirectly protection of G. westfalica cells by SodA from oxidative damage. Both sodA from G. polyisoprenivorans VH2 and sodA from G. westfalica Kb1 coded for polypeptides comprising 209 amino acids and having approximately 90% and 70% identical amino acids, respectively, to the SodA from Mycobacterium smegmatis strain MC(2) 155 and Micrococcus luteus NCTC 2665. As revealed by activity staining experiments with the wild type and the disruption mutant of G. polyisoprenivorans, this bacterium harbors only one active SOD belonging to the manganese family. The N-terminal sequences of the extracellular SodA proteins of both Gordonia species showed no evidence of leader peptides for the mature proteins, like the intracellular SodA protein of G. polyisoprenivorans VH2, which was purified under native conditions from the cells. In G. westfalica Kb1 and G. polyisoprenivorans VH2, SodA probably provides protection against reactive oxygen intermediates which occur during degradation of poly(cis-1,4-isoprene).Applied and environmental microbiology 11/2008; 74(24):7643-53. · 3.69 Impact Factor
Article: Genome Sequence of the Alkaliphilic Bacterial Strain Bacillus ligninesis L1, a Novel Degrader of Lignin.[show abstract] [hide abstract]
ABSTRACT: Bacillus ligninesis strain L1, isolated from seafloor sediment, was able to grow on medium with lignin as its sole carbon source. Here, we report a 3.8-Mbp high-quality genome sequence for this bacterium. The genes involving ectoine and glycine betaine synthesis, as well as those involved in the degradation of lignin, were identified.Genome announcements. 01/2013; 1(2):e0004213.
Article: De novo synthesis of 4,5-dimethoxycatechol and 2, 5-dimethoxyhydroquinone by the brown rot fungus Gloeophyllum trabeum.[show abstract] [hide abstract]
ABSTRACT: The new dimethoxycatechol 4,5-dimethoxy-1,2-benzenediol (DMC) and the new dimethoxyhydroquinone 2,5-dimethoxy-1,4-benzenediol (DMH) were isolated from stationary cultures of the brown rot fungus Gloeophyllum trabeum growing on a glucose mineral medium protected from light. The structure was elucidated by gas chromatography-mass spectrometry through comparison to a synthetic standard. Further confirmation was obtained by forming a dimethoxyoxazole derivative by condensation of DMC with methylene chloride and through examination of methylated derivatives. DMC and DMH may serve as ferric chelators, oxygen-reducing agents, and redox-cycling molecules, which would include functioning as electron transport carriers to Fenton's reactions. Thus, they appear to be important components of the brown rot decay system of the fungus.Applied and Environmental Microbiology 03/1999; 65(2):674-9. · 3.83 Impact Factor