Characterization of diverse natural variants of CYP102A1 found within a species of Bacillus megaterium

An extreme diversity of substrates and catalytic reactions of cytochrome P450 (P450) enzymes is considered to be the consequence of evolutionary adaptation driven by different metabolic or environmental demands. Here we report the presence of numerous natural variants of P450 BM3 (CYP102A1) within a species of Bacillus megaterium. Extensive amino acid substitutions (up to 5% of the total 1049 amino acid residues) were identified from the variants. Phylogenetic analyses suggest that this P450 gene evolve more rapidly than the rRNA gene locus. It was found that key catalytic residues in the substrate channel and active site are retained. Although there were no apparent variations in hydroxylation activity towards myristic acid (C14) and palmitic acid (C16), the hydroxylation rates of lauric acid (C12) by the variants varied in the range of >25-fold. Interestingly, catalytic activities of the variants are promiscuous towards non-natural substrates including human P450 substrates. It can be suggested that CYP102A1 variants can acquire new catalytic activities through site-specific mutations distal to the active site

Analysis of creatine kinase activity with evaluation of protein expression under the effect of heat and hydrogen peroxide

Protein oxidation has detrimental effects on the brain functioning, which involves inhibition of the crucial enzyme, brain type creatine kinase (CKBB), responsible for the CK/phosphocreatine shuttle system. Here we demonstrate a susceptibility of CKBB to several ordinary stressors. In our study enzymatic activity of purified recombinant brain-type creatine kinase was evaluated. We assayed 30 nM concentration of CKBB under normal and stress conditions. In the direction of phosphocreatine formation hydrogen peroxide and heat treatments altered CKBB activity down to 26 and 14%, respectively. Also, examination of immunoblotted membrane patterns by SDS-PAGE electrophoresis and western blot analysis showed a decrease in expression levels of intrinsic CKBB enzyme in HeLa and A549 cells. Hence, our results clearly show that cytosolic CKBB is extremely sensitive to oxidative stress and heat induced inactivation. Therefore, due to its susceptibility, this enzyme may be defined as a potential target in brain damage

Analysis of creatine kinase activity with evaluation of protein expression under the effect of heat and hydrogen peroxide

Protein oxidation has detrimental effects on the brain functioning, which involves inhibition of the crucial enzyme, brain type creatine kinase (CKBB), responsible for the CK/phosphocreatine shuttle system. Here we demonstrate a susceptibility of CKBB to several ordinary stressors. In our study enzymatic activity of purified recombinant brain-type creatine kinase was evaluated. We assayed 30 nM concentration of CKBB under normal and stress conditions. In the direction of phosphocreatine formation hydrogen peroxide and heat treatments altered CKBB activity down to 26 and 14%, respectively. Also, examination of immunoblotted membrane patterns by SDS-PAGE electrophoresis and western blot analysis showed a decrease in expression levels of intrinsic CKBB enzyme in HeLa and A549 cells. Hence, our results clearly show that cytosolic CKBB is extremely sensitive to oxidative stress and heat induced inactivation. Therefore, due to its susceptibility, this enzyme may be defined as a potential target in brain damage

Prx II and CKBB proteins interaction under physiological and thermal stress conditions in A549 and HeLa cells

Peroxiredoxins (Prxs) are versatile enzymes that demonstrate various cell functions as peroxidases, protein chaperones, functions of signal modulators and binding partners. It is well established that Prxs can interact with multiple proteins in cells, such as ASK1, Cdk5-p35, JNK, MIF, PDGF, TKR4 and others. In this study, we attempted to evaluate a possible association between ubiquitous Prx II and ATP/ADP buffering enzyme – brain-type creatine kinase (CKBB). Our co-immunoprecipitation (Co-IP) results from the A549 and HeLa cell lysates with overexpressed HA-Prx II and Flag-CKBB have demonstrated strong association between two proteins under non-stressed conditions. This protein interaction was enhanced by the heat treatment with further HA-Prx II precipitation to the immobilized Flag-CKBB depending on the temperature increase. Temperature induced oligomerization of Prx II may contribute to the formation of Prx II conglomera­tes, which in turn, can associate with CKBB and increase signal intensities on the blotted membranes. Thus, such association and oligomerization of Prx II could take part in recovery and protection of the CKBB enzyme activity from inactivation during heat-induced stress

The Novel role of peroxiredoxin-2 in red cell membrane protein homeostasis and senescence

Peroxiredoxin-2 (Prx2), a typical two-cysteine peroxiredoxin, is the third most abundant protein in red cells. Although progress has been made in the functional characterization of Prx2, its role in red cell membrane protein homeostasis is still under investigation. Here, we studied Prx2−/− mouse red cells. The absence of Prx2 promotes (i) activation of the oxidative-induced Syk pathway; (ii) increased band 3 Tyr phosphorylation, with clustered band 3; and (iii) increased heat shock protein (HSP27 and HSP70) membrane translocation. This was associated with enhanced in vitro erythrophagocytosis of Prx2−/− red cells and reduced Prx2−/− red cell survival, indicating the possible role of Prx2 membrane recruitment in red cell aging and in the clearance of oxidized hemoglobin and damaged proteins through microparticles. Indeed, we observed an increased release of microparticles from Prx2−/− mouse red cells. The mass spectrometric analysis of erythroid microparticles found hemoglobin chains, membrane proteins, and HSPs. To test these findings, we treated Prx2−/− mice with antioxidants in vivo. We observed that N-acetylcysteine reduced (i) Syk activation, (ii) band 3 clusterization, (iii) HSP27 membrane association, and (iv) erythroid microparticle release, resulting in increased Prx2−/− mouse red cell survival. Thus, we propose that Prx2 may play a cytoprotective role in red cell membrane protein homeostasis and senescence

Peroxiredoxin-I is an autoimmunogenic tumor antigen in non-small cell lung cancer

AbstractIn eukaryotic cells, peroxiredoxins are both antioxidants and regulators of H2O2-mediated signaling. We previously found that peroxiredoxin-I (Prx-I) was overexpressed in non-small cell lung cancer (NSCLC) tissue. Since overexpressed protein can induce a humoral immune response, we examined whether serum from NSCLC patients exhibited immunoreactivity against Prx-I using Western blotting. We found that 25 (47%) of 53 NSCLC patients tested had autoantibodies against Prx-I in their sera, whereas such activity was detected in 4 (8%) sera from 50 healthy subjects. Prx-I itself was detected in the sera from 18 (34%) of 53 NSCLC patients but in only 1 (2%) serum from 50 controls. Moreover, 17% of NSCLC sera were positive to both Prx-I antibody and antigen but none in control sera. The data indicate both Prx-I autoantibody and circulating antigen are potential biomarkers for use in serological diagnosis of NSCLC. Interestingly enough, we found that Prx-I was secreted by lung adenocarcinoma cells (A549) but not by non-cancer lung cells (BEAS 2B) or breast cancer cells (MCF7). This cell culture study suggests the possibility of Prx-I secretion from NSCLC tumor tissues