Genome-Wide Assessment of Putative Superoxide Dismutases in Unicellular and Filamentous Cyanobacteria

Abstract Cyanobacteria are photoautotrophic prokaryotes capable to grow in diverse ecological habitats, originated 2.5-3.5 billion years ago and were first to produce oxygen. Since then superoxide dismutases (SOD) acquired great significance due to their ability to catalyze detoxification of byproducts of oxygenic photosynthesis i.e. superoxide radicals. In the present study, we extracted information regarding SODs from species of sequenced cyanobacteria and investigated their diversity, conservation, domain structure, and evolution. 144 putative SOD homologs were identified. Unlike other protein families (ex. serine-threonine kinases) SODs are present in all cyanobacterial species reflecting their significant role in survival. However, their distribution varies fewer (0.01%-0.09%) found in unicellular marine strains whereas abundant (0.02%-0.07%) in filamentous nitrogen-fixing cyanobacteria. They were classified into three major subfamilies according to their domain structures: Fe/MnSOD, Cu/ZnSOD and NiSOD. Interestingly, they lack additional domains as found in proteins of other families however motifs and invariant amino acids typical in eukaryotic SODs were conserved well in these proteins indicating similar catalytic mechanism as eukaryotic SODs. Phylogenetic relationships correspond well with phylogenies based on 16S rRNA and clustering occurs on the basis of structural characteristics such as domain organization. Gene gain-and-loss is insignificant during SOD evolution as evidenced by the absence of additional domain. This study has not only examined an overall background of sequence-structure-function interactions for the SOD gene family but also revealed variation among SOD distribution based on ecophysiological and morphological characters.

Superoxide dismutases and glutaredoxins have a distinct role in the response of Candida albicans to oxidative stress generated by the chemical compounds menadione and diamide

To cope with oxidative stress, Candida albicans possesses several enzymes involved in a number of biological processes, including superoxide dismutases (Sods) and glutaredoxins (Grxs). The resistance of C. albicans to reactive oxygen species is thought to act as a virulence factor. Genes such as SOD1 and GRX2, which encode for a Sod and Grx, respectively, in C. albicans are widely recognised to be important for pathogenesis. We generated a double mutant, Δgrx2/sod1, for both genes. This strain is very defective in hyphae formation and is susceptible to killing by neutrophils. When exposed to two compounds that generate reactive oxygen species, the double null mutant was susceptible to menadione and resistant to diamide. The reintegration of the SOD1 gene in the null mutant led to recovery in resistance to menadione, whereas reintegration of the GRX2 gene made the null mutant sensitive to diamide. Despite having two different roles in the responses to oxidative stress generated by chemical compounds, GRX2 and SOD1 are important for C. albicans pathogenesis because the double mutant Δgrx2/sod1 was very susceptible to neutrophil killing and was defective in hyphae formation in addition to having a lower virulence in an animal model of systemic infection.

Inducibility of superoxide dismutases and metallothionein in the liver and kidney of mice by paraquat with age / 대한내과학회지

BACKGROUND: A number of theories have been proposed to explain the nature of aging process. Unfortunately, there is so far no theory that can completely explain all aging processes. In the present study, to investigate roles of inducibility of defense mechanisms by oxidative stress, cellular mRNA level of superoxide dismutases (SODs) and metallothionein (MT) as well as their inducibility by paraquat, an intracellular superoxide generator, was examined in the liver and kidney of the mice of aging process. METHODS: The steady-state levels of SODs and MT mRNA and their induction by paraquat were determined by the RT-PCR assay in male mice of 4 ages, 1, 4, 8, and 12 months. RESULTS: In the liver, the steady-state levels of Mn-SOD, Cu/Zn-SOD and MT mRNA increased until 8 months with age and decreased significantly at 12 months. Cu/Zn-SOD and MT mRNA were induced well by paraquat at all ages but Mn-SOD mRNA not at 12 months. In the kidney, their mRNA levels of Mn-SOD, Cu/Zn-SOD and MT increased with age. Mn-SOD mRNA was induced by paraquat only at 1 month but Cu/Zn-SOD mRNA not at all ages. On the other hand, MT mRNA was significantly induced by paraquat at all ages. CONCLUSION: These results suggest that SODs and MT are differentially expressed and induced according to the age and organs. In addition, it is thought that the lack of induction of Mn-SOD by oxidative stress in both the liver and kidney may be one of causative factors in the aging process while Cu/Zn-SOD and MT in the liver and MT in the kidney may play protective roles in the aging process. It is therefore implicated that the tissue antioxidant/prooxidant balance could be one of determinants of mean life span.

Role of Inducibility of Superoxide Dismutases and Metallothionein of Mouse Lungs by Paraquat in Aging / 결핵

BACKGROUND: The aging process may be induced, at least in part, by reactive oxygen species(ROS). It has been though that the lung could be a good source of ROS because it has a high oxygen tension. In the present study, we invetigated the inducibility of the first and last lines against oxidative stress, superoxide dismutases (Cu/Zn-SOD and Mn-SOD) as a scavenger of O2- and metallothionein(MT) as a scavenger of OH·, respectively, in mouse lungs with age. METHODS: Oxidative stress was induced by paraquat, an intracellular superoxide generator, at 1, 4, 8, and 12 months of age and then SODs and MT mRNAs were determined by RT-PCR method. RESULTS: The steady-state level of Mn-SOD mRNA increased from 1 to 8 months but decreased thereafter. However, Mn-SOD mRNA was not induced by paraquat after 1 month. On the other hand, there was no change in the steady-state level of Cu/Zn/-SOD mRNA, which decrease abruptly at 12 months of age. Additionally, Cu/Zn/-SOD mRNA was not induced by paraquat at any age. There was no change in the steady-state level of MT mRNA with age whereas its inducibility by paraquat was intact at all ages. CONCLUSION: These results indicate that lack of induction of SODs with age may be one of the causative factors in the aging process while induction of MT may play an important role in the defense against oxidative stress. It is therefore implicated that the tissue antioxidant/proxidant balance could be one determinants of meal life span.

Level of lipid peroxides and cuprozinc superoxide dismutase in gastric mucosa and serum of gastrectomized patients / 第三军医大学学报

The level of lipid peroxides (LPO)and copper-zinc containing superoxide dismutase(SOD-I) in the gastric mucosa and serum was determined in 141 samples from 25 patients after conventional subtotal gastrectomy (11 cases of Billroth I and 14 cases of Billroth Ⅱ and 11 patients after pylorus and antroseromuscular flap preserving gastrectomy (PAFPG).Those of 11 normal subjects were examined likewise to serve as control.It was found that;1.The average LPO level was much higher and the average SOD-I level much lower in the gastric mucosa after conventional subtotal gastrectomy especially the Billroth type Ⅱ than in those after PAFPG.2.In 36 specimens of stump mucosa,the average LPO level was significantly higher in the tissue around the anastomotic ring than in that of the body of the stump;no marked difference of SOD-I level between the 2 was revealed.3.The LPO value in the stump mucosa was positively correlated to and the SOD-I value negatively correlated to the pH value of gastric juice.Thess findings suggest that the reaction of oxygen free radicals in the stump-mucosa may be influenced by the intragastric pH or by the type of digestive continuity reconstruction,and that the reaction of free radicals specially lipidperoxidation may play a role in the pathogenesis of the lesions in the anastomotic stoma.

Purification and characterization of Cu-Zn superoxide dismutases from mungbean (Vigna radiata) seedlings.

Mungbean contains three isoenzymes of superoxide dismutase designated isoenzyme I, II and III. The two cytosolic superoxide dismutases (I and II) were purified to homogeneity by ammonium sulphate fractionation, ion exchange chromatography on diethylaminoethyl cellulose, gel filtration and preparative polyacrylamide·gel electrophoresis. The molecular weights of isoenzyme I and isoenzyme II were determined to be 33,000 and 31,600 respectively. The subunit molecular weight was approximately 16,000 indicating that the isoenzymes contained two identical subunits. The ultra-violet absorption spectra revealed a maximum at 258-264 nm for the two isoenzymes. Superoxide dismutase I and II were inhibited to different extents by metal chelators. Isoenzyme I was more sensitive to inhibition by cyanide and azide, while isoenzyme II was more susceptible to inhibition by diethyldithiocarbamate and o-phenanthroline. Both the isoenzymes exhibited similar denaturation profiles with heat, guanidinium chloride and urea. The denaturation with urea and guanidinium chloride was reversible. The two copper-zinc enzymes were more stable towards thermal inactivation compared to manganese and iron superoxide dismutases from other sources. The results indicate that the two isoenzymes differ from each other only with respect to charge and sensitivity towards metal chelators.

Study on the shock-inducing effect of recombinant human tumor necrosis factor:Changes of lipid peroxidation and leuco-cytic phagocytosis / 第三军医大学学报

After intravenous infusion of recombinant human tumor necrosis factor(TNF)in the dosage of 60?g/kg or 130?g/kg to rabbits,it was found that their plasma malondialde-hyde(MDA)was significantly increased(P

Inununocytochemical Localization Study of Copper-Zinc Superoxide Dismutase in Human Myocardium / 第二军医大学学报

The distribution of copper-zinc superoxide dismutase (Cu-ZnSOD) in subcellular organelles in 8 cases of normal human myocardium was studied by using immunocytochemistry and immunoelectron microscopic technique and the contents of Cu-Zn SOD in myocardium were measured by radioimmunoassay. The results showed that Cu-ZnSOD was in most myocardial cells. The contents of Cu-ZnSOD in the ventricular myocardial cells were higher than those in the atrial myocardial cells. The Cu-ZnSOD labeled with immunogold particles were distributed throughout cytoplasm and nuclei, but less in mitochondria and a very little in lysosomes. No gold particle was found on the membranous structure of sarcoplasmic reticulum as well as Golgi complex. The results demonstrate that the myocardium was the tissue containing quite abundant Cu-Zn SOD.