• BMB Reports
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• v.42 no.9
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• pp.580-585
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• 2009

Dimethyl sulfoxide (DMSO) is widely used in chemistry and biology as a solvent and as a cryoprotectant. It is also used as a pharmaceutical agent for the treatment of interstitial cystitis and rheumatoid arthritis. Previous reports described DMSO as being reduced by methionine-S-sulfoxide reductase (MsrA). However, little is known about the DMSO reduction capability of methionine-R-sulfoxide reductase (MsrB) or its effect on the catalysis of methionine sulfoxide reduction. We show that mammalian MsrB2 and MsrB3 were unable to reduce DMSO. This compound inhibited MsrB2 activity but did not inhibit MsrB3 activity. We further determined that DMSO functions as an inhibitor of MsrA and MsrB2 in the reduction of methionine sulfoxides via different inhibition mechanisms. DMSO competitively inhibited MsrA activity but acted as a non-competitive inhibitor of MsrB2 activity. Our study also demonstrated that DMSO inhibits in vivo methionine sulfoxide reduction in yeast and mammalian cells.

• BMB Reports
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• v.44 no.10
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• pp.669-673
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• 2011

Human methionine sulfoxide reductase B3A (hMsrB3A) is an endoplasmic reticulum (ER) reductase that catalyzes the stereospecific reduction of methionine-R-sulfoxide to methionine in proteins. In this work, we identified an antimicrobial peptide from hMsrB3A protein. The N-terminal ER-targeting signal peptide (amino acids 1-31) conferred an antimicrobial effect in Escherichia coli cells. Sequence and structural analyses showed that the overall positively charged ER signal peptide had an Argand Pro-rich region and a potential hydrophobic ${\alpha}$-helical segment that contains 4 cysteine residues. The potential ${\alpha}$-helical region was essential for the antimicrobial activity within E. coli cells. A synthetic peptide, comprised of 2-26 amino acids of the signal peptide, was effective at killing Gram-negative E. coli, Klebsiella pneumoniae, and Salmonella paratyphi, but had no bactericidal activity against Gram-positive Staphylococcus aureus.

• Journal of Life Science
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• v.19 no.3
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• pp.343-348
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• 2009

Magnaporthe oryzae, a major cause of rice blast, is one of the most destructive plant fungal pathogens. Secretion of reactive oxygen species (ROS) during the infection phase of plant pathogenic fungus plays a key role in the defense mechanism of a plant. ROS causes oxidative damage and functional modification to the proteins in a pathogenic fungus. Methionine, especially, is a major target of ROS, which oxidizes it to methionine sulfoxide. To survive from the attack of ROS, plant pathogenic fungus has antioxidative systems - one example would be methionine sulfoxide reductase B (MSRB), which reverses the oxidative alteration of methionine to methionine sulfoxide. In the present study, identification and molecular characterization of the MSRB gene in M. oryzae KJ201 were investigated. The MSRB gene was amplified by PCR from the M. oryzae KJ201 genomic DNA. The copy number of MSRB in the genome of M. oryzae KJ201 was identified by Southern blot analysis, which revealed that the gene exists as a single copy. To study the molecular function of an MSRB gene, the expression level of the MSRB gene was assayed with hydrogen peroxide treatment by Northern blot analysis and RT-PCR. The expression of the MSRB gene was increased by treatment of hydrogen peroxide, without significant correlation to hydrogen peroxide concentrations. These results indicate that the MSRB gene in M. oryzae KJ201 could contribute to protection against plant defense compounds such as ROS and offer a novel strategy for the control of rice blast.

• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.59-62
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• 2008

The peptide methionine sulfoxide reductases (Msrs) are enzymes that catalyze the reduction of methionine sulfoxide back to methionine. Because of two enantiomers of methionine sulfoxide (S and R forms), this reduction reaction is carried out by two structurally unrelated classes of enzymes, MsrA (E.C. 1.8.4.11) and MsrB (E.C. 1.8.4.12). Whereas MsrA has been well characterized structurally and functionally, little information on MsrB is available. The recombinant MsrB from Bacillus subtilis has been purified and crystallized by the hanging-drop vapor-diffusion method, and the functional and structural features of MsrB have been elucidated. The crystals belong to the trigonal space group P3, with unit-cell parameters a=b=136.096, $c=61.918{\AA}$, and diffracted to $2.5{\AA}$ resolution using a synchrotron-radiation source at Pohang Light Source. The asymmetric unit contains six subunits of MsrB with a crystal volume per protein mass $(V_M)\;of\;3.37{\AA}^3\;Da^{-1}$ and a solvent content of 63.5%.

• BMB Reports
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• v.44 no.12
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• pp.805-810
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• 2011

Methionine sulfoxide reductase A (MSRA) is a ubiquitous enzyme that has been demonstrated to reduce the S enantiomer of methionine sulfoxide (MetSO) to methionine (Met) and can protect cells against oxidative damage. In this study, we isolated a novel MSRA (SlMSRA2) from Micro-Tom (Solanum lycopersicum L. cv. Micro-Tom) and characterized it by subcloning the coding sequence into a pET expression system. Purified recombinant protein was assayed by HPLC after expression and refolding. This analysis revealed the absolute specificity for methionine-S-sulfoxide and the enzyme was able to convert both free and protein-bound MetSO to Met in the presence of DTT. In addition, the optimal pH, appropriate temperature, and $K_m$ and $K_{cat}$ values for MSRA2 were observed as 8.5, $25^{\circ}C$, $352{\pm}25\;{\mu}M$, and $0.066{\pm}0.009\;S^{-1}$, respectively. Disk inhibition and growth rate assays indicated that SlMSRA2 may play an essential function in protecting E. coli against oxidative damage.

• BMB Reports
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• v.43 no.9
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• pp.622-628
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• 2010

Dimethyl sulfoxide (DMSO) can be reduced to dimethyl sulfide by MsrA, which stereospecifically catalyzes the reduction of methionine-S-sulfoxide to methionine. Our previous study showed that DMSO can competitively inhibit methionine sulfoxide reduction ability of yeast and mammalian MsrA in both in vitro and in vivo, and also act as a non-competitive inhibitor for mammalian MsrB2, specific for the reduction of methionine-R-sulfoxide, with lower inhibition effects. The present study investigated the effects of DMSO on the physiological antioxidant functions of methionine sulfoxide reductases. DMSO elevated hydrogen peroxide-mediated Saccharomyces cerevisiae cell death, whereas it protected human SK-Hep1 cells against oxidative stress. DMSO reduced the protein-carbonyl content in yeast cells in normal conditions, but markedly increased protein-carbonyl accumulation under oxidative stress. Using Msr deletion mutant yeast cells, we demonstrated the DMSO's selective inhibition of the antioxidant function of MsrA in S. cerevisiae, resulting in an increase in oxidative stress-induced cytotoxicity.

• BMB Reports
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• v.28 no.1
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• pp.17-20
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• 1995

Thioredoxin reductase is a flavoprotein oxidoreductase catalyzing the reduction of a cystine disulfide in thioredoxin. Thioredoxin, in turn, can reduce disulfide bonds in other proteins and serves as a reducing agent in enzymatic reactions such as those of ribonucleotide reductase and methionine sulfoxide reductase. In this work thioredoxin reductase was found to directly reduce DTNB in the absence of thioredoxin. This new reactivity of E. coli thioredoxin reductase was produced by relatively high concentrations of univalent cations such as $Na^+$, $K^+$, $Li^+$, and ${NH_4}^+$, and it appeared with the oxidation of NADPH. These results indicate that E. coli thioredoxin reductase may be slightly modified by univalent cations, and the modified enzyme directly reacts with DTNB. This DTNB-reducing activity offers a new assay method for E. coli thioredoxin reductase.

• BMB Reports
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• v.42 no.2
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• pp.113-118
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• 2009

Despite the growing body of evidence suggesting a role for MsrA in antioxidant defense, little is currently known regarding the function of MsrB in cellular protection against oxidative stress. In this study, we overexpressed the mammalian MsrB and MsrA genes in Saccharomyces cerevisiae and assessed their subcellular localization and antioxidant functions. We found that the mitochondrial MsrB3 protein (MsrB3B) was localized to the cytosol, but not to the mitochondria, of the yeast cells. The mitochondrial MsrB2 protein was detected in the mitochondria and, to a lesser extent, the cytosol of the yeast cells. In this study, we report the first evidence that MsrB3 overexpression in yeast cells protected them against $H_2O_2$-mediated cell death. Additionally, MsrB2 overexpression also provided yeast cells with resistance to oxidative stress, as did MsrA overexpression. Our results show that mammalian MsrB and MsrA proteins perform crucial functions in protection against oxidative stress in lower eukaryotic yeast cells.

• Journal of Life Science
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• v.33 no.5
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• pp.445-454
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• 2023

Hair graying is the result of a malfunction in the signaling pathways that control melanogenesis, and it is activated by UV light, melanocyte-stimulating hormone (MSH), stem cell factor (SCF), Wnt, and endothelin-1 (ET-1). To prevent hair graying, synthetic and natural compounds can be used to stimulate melanogenesis effectively under the control of tyrosinase, tyrosine hydroxylase, tyrosinase-related protein-1 (TRP-1), TRP-2, and microphthalmia-associated transcription factor (MITF). This article describes a crucial strategy to resolve the problem of hair graying, as well as recent advances in the signaling pathway related to melanogenesis and hair graying. In particular, the article reviews potentially effective therapeutic agents that promote melanogenesis, such as antioxidants that modulate catalase, methionine sulfoxide reductase, and sirtuin 1 (SIRT1) activators including resveratrol, fisetin, quercetin, and ginsenoside. It also discusses vitiligo inhibitors, such as corticosteroids, calcineurin inhibitors, and palmitic acid methyl ester, as well as activators of telomerase expression and activity, including estrogen, androgen, progesterone, and dihydrotestosterone. Furthermore, it explores compounds that can inhibit hair graying, such as latanoprost, erlotinib, imatinib, tamoxifen, and levodopa. In conclusion, this article focuses on recent research trends on compounds that promote melanin production related to hair graying.

• BMB Reports
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• v.44 no.4
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• pp.256-261
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• 2011

PEP-1 peptide has been used for transduction of native protein into mammalian cells. This work describes the findings that the fusion of PEP-1 to target proteins led to protein truncation likely in a non-protein-specific manner. Approximately 75% of PEP-1-MsrA fusion protein was truncated in the N-terminal region of MsrA between Lys-27 and Val-28 during expression in Escherichia coli and purification. This large protein truncation was also observed in another PEP-1 fused protein, PEP-1-MsrB2, in the N-terminal region of MsrB2. The full-length PEP-1-MsrA protein was rapidly transduced into keratinocyte cells within 15 min. The transduced PEP-1-MsrA was functionally active and could protect skin cells against oxidative stress- and ultraviolet radiation-induced cell death. Collectively, our data demonstrated the protective roles of MsrA in skin cells and, moreover, may raise a concern of protein truncation caused by fusion of PEP-1 about the general use of this peptide for protein transduction.