Bioscience, Biotechnology, and Biochemistry
Online ISSN : 1347-6947
Print ISSN : 0916-8451
Volume 75 , Issue 5
Showing 1-38 articles out of 38 articles from the selected issue
Award Review
  • Nobuyuki MARUYAMA, Bunzo MIKAMI, Shigeru UTSUMI
    2011 Volume 75 Issue 5 Pages 823-828
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Supplementary material
    Seed storage proteins are a major component of mature seeds. They are utilized as protein sources in foods. We designed seed storage proteins containing bioactive peptides based on their three-dimensional structures. Furthermore, to create crops with enhanced food qualities, we developed transgenic crops producing seed storage proteins with bioactive peptides. This strategy promises to prevent lifestyle-related diseases by simple daily food consumption. In this review, we discuss a strategy to develop transgenic crops to improve human health by advanced utilization of seed storage proteins.
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Analytical Chemistry Regular Paper
  • Naoki MATSUNAGA, An-na KATO, Norio MURASE
    2011 Volume 75 Issue 5 Pages 899-903
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    The interaction between lecithin liposomes and acid clay was investigated to clarify the mechanism for liposome adsorption to the clay. It was found that the multilamellar vesicular structure of the liposomes was broken as a result of primary adsorption. The acid clay particles aggregated and were eventually covered by the lecithin layer structure. In the case of kaolin, on the other hand, the liposomes were weakly adsorbed to the clay and maintained the vesicular structure. The amount of primary adsorption to the clay surface, which was estimated from the adsorption isotherm, was more for acid clay than for kaolin, and the total amount adsorbed to the acid clay was also more than to kaolin. This result can be explained by the much higher density of the negative charge on the acid clay surface than that for kaolin. The liposomes are therefore considered to be adsorbed to the acid clay mainly by the choline positive charge residing at the end of the lecithin molecule, although this is of no net charge as a whole.
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Organic Chemistry Regular Papers
Organic Chemistry Note
Biochemistry & Molecular Biology Regular Papers
  • Yeon-Joo KWAK, Kyoung-Sook KIM, Kyung-Mi KIM, Hai Yang YU, Eunsook CHU ...
    2011 Volume 75 Issue 5 Pages 841-847
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    We assessed the effects of chloroform extract of fermented Viola mandshurica (CEFV) on melanogenesis B16 melanoma cells. CEFV treatment significantly decreased melanin content and tyrosinase activity in dose-dependent manners. To elucidate the mechanism of the inhibitory effects of CEFV on melanogenesis, we performed RT-PCR and Western blotting for melanogenesis-related genes such as tyrosinase, tyrosinase-related protein-1 (TRP-1), TRP-2, and microphthalmia-associated transcription factor (MITF). CEFV strongly inhibited mRNA as well as the protein expression of tyrosinase and MITF, but had no significant effect on TRP-1 or TRP-2 expressions. It markedly decreased the phosphorylation of cAMP responsive element binding protein (CREB), and induced the duration of extracellular signal-regulated kinase (ERK) activation, leading to reduction of MITF expression and subsequently that of tyrosinase. Therefore, we suggest that CEFV induces downregulation of melanogenesis through decreased CREB phosphorylation and ERK activation.
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  • Lan XIANG, Kaiyue SUN, Jun LU, Yufang WENG, Akiko TAOKA, Youji SAKAGAM ...
    2011 Volume 75 Issue 5 Pages 854-858
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    The anti-aging effects of phloridzin on the yeast Saccharomyces cerevisiae were investigated by employing a replicative lifespan assay of the K6001 yeast strain. After administrating phloridzin at doses of 3, 10, and 30 μM, the lifespan of the yeast was significantly prolonged in comparison with the untreated group (p<0.01, p<0.001). To determine the mechanism of action, anti-oxidative experiments and ROS assay were performed. Phloridzin improved the viability of the yeast dose-dependently under oxidative stress by 7.5 mM H2O2, and a low dose of phloridzin inhibited ROS of the yeast. Further, SOD1, SOD2, and Sir2 gene expression was examined by reverse transcription-polymerase chain reaction (RT-PCR), and was found to be significantly increased. Finally, superoxide dismutase (SOD) and SIRT1 activity assays showed that phloridzin notably increased the activity of SOD and SIRT1. These results suggest that SOD and Sir2 have important roles in phloridzin-regulated lifespan extension of yeast, and potentially anti-aging effects for mammalian cells via SIRT1.
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  • Tatsuo MURAKAMI, Nobuyuki KAMIKADO, Ryo FUJIMOTO, Kazuhiko HAMAGUCHI, ...
    2011 Volume 75 Issue 5 Pages 864-870
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Protobothrops flavoviridis venom contains plural phospholipase A2 (PLA2) isozymes. A [Lys49]PLA2 called BPII induced cell death in human leukemia cells. PLA2, an [Asp49]PLA2 that has much stronger lipolytic activity than BPII, failed to induce cell death. BPII-treated cells showed morphological changes, DNA fragmentation, and nuclear condensation. This BPII-induced apoptotic cell death was neither inhibited by inhibitors of caspases 3 and 6 nor accompanied by activation of procaspase 3, indicating that BPII-induced cell death is caspase independent. Since inactive p-bromophenacylated BPII induced cell death, BPII-induced apoptotic cell death is independent of PLA2 lipolytic activity. Rapid externalization of phosphatidylserine in BPII-treated cells was observed for fluorescein isothiocyanate (FITC)-labeled annexin V. In the cells treated with BPII, this spread over the cell membranes, implying that the cell toxicity of BPII is mediated via its cell-surface receptor.
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  • Masayuki WATANABE, Atsuko MIYAGI, Minoru NAGANO, Maki KAWAI-YAMADA, Hi ...
    2011 Volume 75 Issue 5 Pages 877-881
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Supplementary material
    Rumex obtusifolius L., a member of Polygonaceae, is one of the world’s worst weeds. We characterized the glucosylceramide molecular species in leaves of R. obtusifolius by liquid chromatography/tandem mass spectrometry. 4,8-Sphingadienines were principally paired with 2-hydroxy palmitic acids. In contrast, 4-hydroxy-8-sphingenines were chiefly attached to 2-hydroxy fatty acids with 22 to 26 carbon-chain length. A unique characteristic of the 2-hydroxy fatty acid composition of R. obtusifolius was the high content of n-9 monoenoic 2-hydroxy fatty acids with 22 and 24 carbon-chain length. The levels of the Z and E stereoisomers of the 8-unsaturated long-chain bases were reliably distinguished from those in other plant families in ten species of Polygonaceae.
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  • Takeshi MATSUI, Yuki NOMURA, Mai TAKANO, Sofue IMAI, Hideki NAKAYAMA, ...
    2011 Volume 75 Issue 5 Pages 882-890
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Supplementary material
    Portulaca (Portulaca oleracea cv.) efficiently removes phenolic pollutants from hydroponic solution. In plant roots, peroxidase (PRX) is thought to be involved in the removal of phenolic pollutants by the cross-linking them to cell wall polysaccharides or proteins at the expense of reduction of hydrogen peroxide (H2O2). In this study, we found that portulaca roots secreted an acidic PRX isozyme that had relatively high H2O2 affinity. We isolated five PRX genes, and the recombinant PRX proteins produced in cultured tobacco cells were partially characterized. Among these genes, PoPRX2 probably encoded the acidic PRX isozyme. PoPRX2 had an extra N-terminal region which has not been reported for other PRX proteins. We found that PoPRX2 oxidized phenolic pollutants, including bisphenol A, octylphenol, nonylphenol, and 17β-estradiol. In addition, we found that the Cys261 residue of PoPRX2 played an important role in the determination of affinity for H2O2 and stability toward H2O2.
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  • Victor C. LIN, Hsiou-Yu DING, Pin-Chin TSAI, Jiumn-Yih WU, Yen-Hsing L ...
    2011 Volume 75 Issue 5 Pages 914-918
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Our previous study showed that a methanol extract from Trifolium pratense exerted potent inhibitory activity on melanogenesis in mouse B16 melanoma cells. In the present study, the active compound in this Chinese herb extract was isolated and identified as biochanin A by mass spectrum, 1H-NMR, and 13C-NMR analysis. The inhibitory effects of biochanin A on melanogenesis were investigated in vitro in cultured melanoma cells and in vivo in zebrafish and mice. Biochanin A dose-dependently inhibited both melanogenesis and cellular tyrosinase activity in B16 cells and in zebrafish embryos. Application of a cream containing 2% biochanin A twice daily to the skin of mice also increased the skin-whitening index value after 1 week of treatment, and the increase continued for another 2 weeks. Biochanin A was confirmed as a good candidate for use as a skin-whitening agent in the treatment of skin hyperpigmentation disorders.
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  • Taku IWAMOTO, Kiyoshi YAMADA, Makoto SHIMIZU, Mamoru TOTSUKA
    2011 Volume 75 Issue 5 Pages 925-929
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Small and large intestinal epithelial cell (IEC) lines were established from adult murine intestinal crypts. Both established small and large IECs line (named aMoS7 and aMoC1 respectively) expressed epithelial markers. Similarly to IECs isolated from adult mouse intestines, the expression of major histocompatibility complex (MHC) class II molecules was induced by interferon-γ-treatment in both established cell lines. This expression of MHC class II molecules was higher in small intestinal aMoS7 cells than in large intestinal aMoC1 cells. Treatment with lipopolysaccharide and with ligands of Toll-like receptors 1, 2, 3, and 7 induced secretion of interleukin-6 from both adult IEC lines. These results suggest that the aMoS7 and aMoC1 cell lines can serve as useful tools in analyzing the immunological functions of IECs, especially in studying the IEC response to microbial components and its antigen presenting ability.
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  • Lii Mien YEE, Takashi MATSUMOTO, Koichi YANO, Satoshi MATSUOKA, Yoshit ...
    2011 Volume 75 Issue 5 Pages 944-952
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Supplementary material
    A nucleotide sequence of the whole genome of Bacillus subtilis phage SP10 was determined. It was composed of 143,986 bp with 236 putative open reading frames (ORFs). Sixty-five of 236 predicted ORFs showed high similarity to that of SPO1, and the genome organizations of the two phages were similar to each other. SP10 belongs to the Myoviridae family, for which the well-studied phage SPO1 is the representative phage. Hence, we compared SP10 to SPO1. The SP10 genome DNA showed different sensitivity to restriction enzymes than SPO1, due to differences in base modification. According to transcriptional analysis, the gene expression of regulatory network of SP10 was similar to SPO1. It was observed that RNA polymerase containing sigma-A was inactive in directing the host genes but active in directing the phage genes. It appeared that the association of sigma-A with the core enzyme complex of RNA polymerase was strengthened during development.
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  • Yong ZHAO, Gyung-Hyun JO, Wan-Taek JU, Woo-Jin JUNG, Ro-Dong PARK
    2011 Volume 75 Issue 5 Pages 960-965
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Chitin deacetylase (CDA), the enzyme that catalyzes the hydrolysis of acetamido groups of GlcNAc in chitin, was purified from culture filtrate of the fungus Mortierella sp. DY-52 and characterized. The extracellular enzyme is likely to be a highly N-glycosylated protein with a pI of 4.2–4.8. Its apparent molecular weight was determined to be about 52 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS–PAGE) and 67 kDa by size-exclusion chromatography. The enzyme had an optimum pH of 6.0 and an optimum temperature of 60 °C. Enzyme activity was slightly inhibited by 1–10 mM Co2+ and strongly inhibited by 10 mM Cu2+. It required at least two GlcNAc residues for catalysis. When (GlcNAc)6 was used as substrate, Km and Vmax were determined to be 1.1 mM and 54.6 μmol min−1 respectively.
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  • Koichi YANO, Hiromi INOUE, Hirokazu MORI, Lii Mien YEE, Satoshi MATSUO ...
    2011 Volume 75 Issue 5 Pages 966-975
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Pairs of the ECF sigma factor and its anti-sigma factor, SigW and RsiW, of Bacillus-related species that inhabit extreme environments were heterologously expressed in B. subtilis. All the RsiWs, membrane proteins, failed to fill their function of repressing cognate SigW activity, despite their close structural similarities. Particularly, uncontrolled expression of Oceanobacillus iheyensis OISigW due to abortive OIRsiW was harmful to B. subtilis. Analysis of revertants of this growth defect and site-directed mutagenesis indicated that the insertion of six and a minimum of three hydrophobic amino acid residues occurring in the transmembrane region allowed OIRsiW to function as anti-OISigW. Subcellular localization of OIRsiW was detected by immunoblot analysis, suggesting that both the wild-type and the mutant form of OIRsiW were localized to the membrane. An appropriate length of a transmembrane region required for proper integration into the membrane after translocation might vary among these Bacillus-related species.
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Biochemistry & Molecular Biology Notes
Biochemistry & Molecular Biology Communications
Food & Nutrition Science Regular Papers
  • Kanako AMAKI, Eri SAITO, Kumiko TANIGUCHI, Keiko JOSHITA, Masatsune MU ...
    2011 Volume 75 Issue 5 Pages 829-832
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Chlorogenic acid (CQA) is one of the major polyphenols in apple and a good substrate for the polyphenol oxidase (PPO) in apple. Apple contains catechins as well as CQA, and the role of CQA quinone and its interaction with catechins in the enzymatic browning of apple were examined. Browning was repressed and 2-cysteinyl-CQA was formed when cysteine was added to apple juice. CQA quinone was essential for browning to occur. Although catechins and CQA were oxidized by PPO, some catechins seemed to be non-enzymatically oxidized by CQA quinone.
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  • Sang-Won HONG, Kyung Hee JUNG, Hee-Seung LEE, Hong-Mei ZHENG, Myung-Jo ...
    2011 Volume 75 Issue 5 Pages 833-840
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Fucoidan, a sulfated polysaccharide extracted from various types of brown seaweed, possesses a wide range of pharmacological properties. We investigated the protective effect of fucoidan on dimethylnitrosamine-induced liver fibrogenesis in rats and its mechanism. Liver fibrosis was induced by injecting DMN (10 mg/kg, 3 times per week, I.P.) for 4 weeks, and fucoidan was simultaneously administered (100 mg/kg, 3 times per week, P.O.). The anti-oxidative and anti-inflammatory effects of fucoidan were observed by relative mediators. Fucoidan improved liver fibrosis by inhibiting the expression of transforming growth factor beta 1 (TGF-β1)/Smad3 and the tissue inhibitor of metalloproteinase 1 (TIMP-1), and increasing the expression of metalloproteinase-9 (MMP-9). Fucoidan also significantly decreased the accumulation of the extracellular matrix (ECM) and collagen. These results suggest that fucoidan had an anti-fibrotic effect, which was exerted by inhibiting the TGF-β/Smad pathway, as well as anti-oxidative and anti-inflammatory effects.
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  • Md. Kaosar Niaz Bin SUFIAN, Tohru HIRA, Toshihiro NAKAMORI, Hitoshi FU ...
    2011 Volume 75 Issue 5 Pages 848-853
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    A peptic digest of soybean β-conglycinin (BconP) suppresses the appetite in rats through cholecystokinin (CCK) secretion by enteroendocrine cells. We investigate in this study more appetite-suppressing hydrolysates. β-Conglycinin hydrolyzed with food-processing proteases thermolysin (BconT), bromelain (BconB), chymotrypsin, protease S, and protease M was examined for CCK-secreting activity in a CCK-producing cell line for comparison with BconP. The potent CCK-releasing hydrolysates were then tested for their suppression of the food intake by rats. BconB, BconT, and BconP stimulated high CCK secretion, with the highest by BconB. Orogastric preloading by BconB, but not by BconT, suppressed the 60-min food intake. A meal-feeding trial twice a day in the morning (a.m.) and evening (p.m.) for 10 d showed that BconB preloading before every meal attenuated the p.m. meal size, but not that a.m., resulting in an overall reduction of the daily meal size. These results demonstrate that the bromelain hydrolysate of β-conglycinin having potent CCK-releasing activity suppressed the appetite of rats under meal-feeding conditions.
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  • Manami YAMAWAKI, Kosuke NISHI, Sogo NISHIMOTO, Satoshi YAMAUCHI, Koich ...
    2011 Volume 75 Issue 5 Pages 859-863
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Matairesinol is one of the lignan compounds found in a variety of plant foodstuffs. We investigated the immunomodulatory effects of (−)-matairesinol in vivo and ex vivo by using mice. Although we found no significant differences in the IgG, IgA and IgM levels in the serum, the IgE level was strongly suppressed by the uptake of (−)-matairesinol in both intact and ovalbumin-immunized mice. The immunoglobulin produced by lymphocytes from the spleen was not activated by the intake of (−)-matairesinol. However, lymphocytes in such gut-associated lymphatic tissues as Peyer’s patches and mesenteric lymph nodes were activated by the administration of (−)-matairesinol.
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  • Young Na PARK, Youn Ju LEE, Jeon Hyeun CHOI, Meihua JIN, Ju Hae YANG, ...
    2011 Volume 75 Issue 5 Pages 871-876
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    The flowers of Inula japonica (Inulae Flos) have long been used in traditional medicine for treating inflammatory diseases. The effects on OVA-induced asthmatic mice of an Inulae Flos extract (IFE) were evaluated in this study. The anti-asthmatic effects of IFE were determined by observing eosinophil recruitment, airway hyper-responsiveness (AHR), Th2 cytokine and IgE levels, and lung histopathology. The IFE treatment effectively reduced the percentage of eosinophils and Th2 cytokines in the bronchoalveolar lavage fluid (BALF) when compared to the levels in OVA-induced mice. IFE also suppressed AHR induced by aerosolized methacholine in OVA-induced mice. The results of the histopathological studies indicate that inflammatory cell infiltration and mucus hypersecretion were both inhibited by the IFE administration when compared to the effect on OVA-induced mice. The IFE treatment also suppressed the serum IgE levels and decreased Th2 cytokines in the supernatant of cultured splenocytes. These results suggest that IFE may have therapeutic potential against asthma.
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  • HongHui BAO, SangGuan YOU
    2011 Volume 75 Issue 5 Pages 891-898
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    Water-soluble extracts isolated from Hypsizigus marmoreus and fractionated by ion-exchange chromatography were investigated to determine their molecular characteristics and biological activities. The crude and fractionated water-soluble extracts (F1, F2 and F3) consisted mostly of carbohydrates (55.8–98.9%) with varied protein contents (1.1–23.0%). Their monosaccharide levels were significantly different, including the glucose content (67.0–100%) and galactose content (0–33.0%). The backbone of each fraction was mainly glucose molecules connected with 1,4-glycosidic linkages which contained considerable amounts of glucose and/or galactose connected through 1,6-glycosidic linkages. The average molecular weight (Mw) of the extracts varied considerably, ranging from 1,665×104 to 19×104 g/mol. Little cytotoxicity was apparent in cancer cell lines from the addition of these extracts; however, they significantly stimulated Raw 264.7 cells to release nitric oxide (NO) and prostaglandin E2 (PGE2), suggesting their potential immunomodulating activities.
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  • Yusaku IWASAKI, Yasuko TAMURA, Kimiko INAYOSHI, Masataka NARUKAWA, Ken ...
    2011 Volume 75 Issue 5 Pages 904-909
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    The administration of such a transient receptor potential vanilloid 1 (TRPV1) agonist as capsaicin, which is a pungent ingredient of red pepper, promotes energy metabolism and suppresses visceral fat accumulation. We have recently identified monoacylglycerols (MGs) having an unsaturated long-chain fatty acid as the novel TRPV1 agonist in foods. We investigated in this present study the effects of dietary MGs on uncoupling protein 1 (UCP1) expression in interscapular brown adipose tissue (IBAT) and on fat accumulation in mice fed with a high-fat, high-sucrose diet. The MG30 diet that substituted 30% of all lipids for MGs (a mixture of 1-oleoylglycerol, 1-linoleoylglycerol and 1-linolenoylglycerol) significantly increased the UCP1 content of IBAT and decreased the weight of epididymal white adipose tissue, and the serum glucose, total cholesterol and free fatty acid levels. The diet containing only 1-oleoylglycerol as MG also increased UCP1 expression in IBAT. MGs that activated TRPV1 also therefore induced the expression of UCP 1 and prevented visceral fat accumulation as well as capsaicin.
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Food & Nutrition Science Notes
Microbiology & Fermentation Technology Regular Papers
  • Ying-Yu JIN, Jinhua CHENG, Seung Hwan YANG, Lingzhu MENG, Sasikumar Ar ...
    2011 Volume 75 Issue 5 Pages 910-913
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    S-Adenosyl-L-methionine (SAM) is one of the major methyl donors in all living organisms. The exogenous treatment with SAM leads to increased actinorhodin production in Streptomyces coelicolor A3(2). In this study, mutants from different stages of the AfsK-AfsR signal transduction cascade were used to test the possible target of SAM. SAM had no significant effect on actinorhodin production in afsK, afsR, afsS, or actII-open reading frame 4 (ORF4) mutant. This confirms that afsK plays a critical role in delivering the signal generated by exogenous SAM. The afsK-pHJL-KN mutant did not respond to SAM, suggesting the involvement of the C-terminal of AfsK in binding with SAM. SAM increased the in vitro autophosphorylation of kinase AfsK in a dose-dependent manner, and also abolished the effect of decreased actinorhodin production by a Ser/Thr kinase inhibitor, K252a. In sum, our results suggest that SAM activates actinorhodin biosynthesis in S. coelicolor M130 by increasing the phosphorylation of protein kinase AfsK.
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  • Hideyuki TAMEGAI, Yuuya OTA, Minami HAGA, Hiroki FUJIMORI, Chiaki KATO ...
    2011 Volume 75 Issue 5 Pages 919-924
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    The facultative piezophile Shewanella violacea DSS12 is known to alter its respiratory components under the influence of hydrostatic pressure during growth, suggesting that it has a respiratory system that functions in adaptation to high pressure. We investigated the pressure- and temperature-dependencies of the respiratory terminal oxidase activity of the membrane of S. violacea relative to non-piezophilic Shewanella species. We observed that the activity in the membrane of S. violacea was more resistant to high pressure than those of non-piezophilic Shewanella even though DSS12 was cultured under atmospheric pressure. On the other hand, the temperature dependency of this activity was almost the same for all of the tested strain regardless of optimal growth temperature. Both high pressure and low temperature are expected to lower protein flexibility, causing a decrease in enzyme activity, but the results of this study suggest that the mechanism maintaining enzyme activity under high hydrostatic pressure is different from that at low temperature. Additionally, the responses of the activity to the pressure- and temperature-changes were independent of membrane lipid composition. Therefore, the piezotolerance of the respiratory terminal oxidases of S. violacea is perhaps dependent on the properties of the protein itself and not on the lipid composition of the membrane. Our observations suggest that S. violacea constitutively express piezotolerant respiratory terminal oxidases that serve adaptation to the deep-sea environment.
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  • Hiroshi YONEYAMA, Hatsuhiro HORI, Sang-Jo LIM, Tatsuya MURATA, Tasuke ...
    2011 Volume 75 Issue 5 Pages 930-938
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    For Escherichia coli, it has been assumed that L-alanine is synthesized by alanine-valine transaminase (AvtA) in conjunction with an unknown alanine aminotransferase(s). We isolated alanine auxotrophs from a prototrophic double mutant deficient in AvtA and YfbQ, a novel alanine aminotransferase, by chemical mutagenesis. A shotgun cloning experiment identified two genes, uncharacterized yfdZ and serC, that complemented the alanine auxotrophy. When the yfdZ- or serC-mutation was introduced into the double mutant, one triple mutant (avtA yfbQ yfdZ) showed alanine auxotrophy, and another (avtA yfbQ serC), prototrophy. In addition, we found that four independent alanine auxotrophs possessed a point mutation in yfdZ but not in serC. We also found that yfdZ expression was induced in minimal medium. Furthermore, yfbQ-bearing plasmid conferred the ability to excrete alanine on the mutant lacking D-amino acid dehydrogenase-encoding gene, dadA. From these results, we concluded that E. coli synthesizes L-alanine by means of three aminotransferases, YfbQ, YfdZ, and AvtA.
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  • Yuji NOGUCHI, Hisaki TANAKA, Kyoko KANAMARU, Masashi KATO, Tetsuo KOBA ...
    2011 Volume 75 Issue 5 Pages 953-959
    Published: May 23, 2011
    Released: May 30, 2011
    [Advance publication] Released: May 20, 2011
    JOURNALS FREE ACCESS
    XlnR is a transcription factor that mediates D-xylose-triggered induction of xylanolytic and cellulolytic genes in Aspergillus. In order to clarify the molecular mechanisms underlying XlnR-mediated induction, Aspergillus oryzae XlnR was fused with the c-myc tag and examined by Western blotting. Phosphate-affinity SDS–PAGE revealed that XlnR was present as a mixture of variously phosphorylated forms in the absence of D-xylose, and that D-xylose triggered additional phosphorylation of the protein. D-Xylose-triggered phosphorylation was a rapid process occurring within 5 min prior to the accumulation of xynG2 mRNA, and removal of D-xylose caused slow dephosphorylation, leading to less-phosphorylated forms. At 30 min after removal, the phosphorylation status was almost identical to that in the absence of D-xylose, and the level of xynG2 mRNA started to decrease. These results indicate that XlnR is highly phosphorylated when it is active in transactivation, implying that D-xylose-triggered reversible phosphorylation controls XlnR activity.
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Microbiology & Fermentation Technology Notes
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