Bioscience, Biotechnology, and Biochemistry
Online ISSN : 1347-6947
Print ISSN : 0916-8451
Volume 76 , Issue 3
Showing 1-37 articles out of 37 articles from the selected issue
Analytical Chemistry Note
Organic Chemistry Regular Paper
  • Ying LI, Shinya MITSUHASHI, Makoto IKEJO, Nobuaki MIURA, Takeshi KAWAM ...
    2012 Volume 76 Issue 3 Pages 486-494
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
    JOURNALS FREE ACCESS
    Supplementary material
    The optimal cellular responses to DNA damage are modulated by kinase and phosphatase. The ataxia telangiectasia mutated (ATM) is a Ser/Thr kinase which is the core of the DNA damage signaling apparatus. The Ser/Thr protein phosphatase type 1 (PP1) inhibitor, tautomycetin (TC) and an antibody to the phospho-(S/T)Q sites of the ATM substrate were used to identify the common substrates for PP1 and ATM in regulating the pathway for DNA damage response. Ribosomal protein S6 (RPS6) was first identified as a substrate for PP1 and ATM. The phosphorylation at Ser247 of RPS6 was then significantly decreased by PP1-mediated dephosphorylation immediately after UV irradiation. These results suggest that PP1 specifically dephosphorylated RPS6 at phospho-Ser247 in vivo. In response to DNA damage, ATM activity was finally required for the phosphorylation of RPS6 at Ser247. We propose from these results a novel mechanism for modulating the RPS6 function by PP1 and ATM which regulates cell growth and survival in response to DNA-damage stimuli.
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Organic Chemistry Note
Biochemistry & Molecular Biology Regular Papers
  • Shinya NAKAMURA, Takamasa SUZUKI, Makoto KAWAMUKAI, Tsuyoshi NAKAGAWA
    2012 Volume 76 Issue 3 Pages 436-446
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Supplementary material
    Small proteins secreted to the extracellular matrix in plants regulate many physiological activities, including pathogen response, material transport, and morphogenesis, but the functions of most small secreted proteins have not been elucidated except for some well-known small secreted proteins. To predict the functions and physiological roles of unidentified small secreted proteins, information on their expression patterns is valuable. Here, we report expression analysis of Arabidopsis thaliana small secreted protein (ATSP) genes that encode proteins possessing a signal peptide at N-terminal, and protein sizes were less than 100 amino acid residues. By promoter:reporter experiments, we examined the expression of 122 ATSPs, including 47 unannotated ATSPs that do not have any discernable motifs, in tissues and at the cellular level in Arabidopsis seedlings, and floral organs. As a result, 79 ATSP genes were expressed in various regions of the seedlings, and 37 ATSP genes were specifically expressed.
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  • Noriya MASAMURA, Wakana OHASHI, Nobuaki TSUGE, Shinsuke IMAI, Anri ISH ...
    2012 Volume 76 Issue 3 Pages 447-453
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Supplementary material
    Lachrymatory factor synthase (LFS), an enzyme essential for the synthesis of the onion lachrymatory factor (propanethial S-oxide), was identified in 2002. This was the first reported enzyme involved in the production of thioaldehyde S-oxides via an intra-molecular H+ substitution reaction, and we therefore attempted to identify the catalytic amino acid residues of LFS as the first step in elucidating the unique catalytic reaction mechanism of this enzyme. A comparison of the LFS cDNA sequences among lachrymatory Allium plants, a deletion analysis and site-directed mutagenesis enabled us to identify two amino acids (Arg71 and Glu88) that were indispensable to the LFS activity. Homology modeling was performed for LFS/23–169 on the basis of the template structure of a pyrabactin resistance 1-like protein (PYL) which had been selected from a BLASTP search on SWISS-MODEL against LFS/23–169. We identified in the modeled structure of LFS a pocket corresponding to the ligand-binding site in PYL, and Arg71 and Glu88 were located in this pocket.
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  • Tohru KOBAYASHI, Kohsuke UCHIMURA, Osamu KOIDE, Shigeru DEGUCHI, Koki ...
    2012 Volume 76 Issue 3 Pages 506-511
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    An alkaline κ-carrageenase, Cgk-K142, was found in the culture broth of a deep-sea bacterium, Pseudoalteromonas tetraodonis JAM-K142. A gene for the enzyme was cloned and expressed. Purified recombinant Cgk-K142 (rCgk-K142) showed an optimal pH of about 8.8 in glycine-NaOH buffer at 30 °C and of about 8.0 in MOPS buffer at 50 °C. The optimal temperature for the enzyme was 55 °C at pH 8.0. rCgk-K142 was unstable, but λ- and ι-carrageenans, non-degradative substrate homologs, extensively enhanced its stability. The nucleotide sequence of the gene for Cgk-K142 comprised 1,194 bp, and the deduced amino acid sequence (397 amino acids) showed a high level of similarity to the κ-carrageenase of P. carrageenovora, with 94% identity. Another gene for a κ-carrageenase-like protein was found downstream of the gene for Cgk-K142. The nucleotide sequence of that gene consisted of 966 bp (321 amino acids), and it showed the highest similarity, at 64% identity, to protein CgkB of P. carrageenovora, which has been reported as an incomplete 57-amino acid sequence.
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  • Keisuke HARA, Yuko INADA, Takuya ONO, Kouichi KURODA, Yoshimi YASUDA-K ...
    2012 Volume 76 Issue 3 Pages 512-516
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Despite many recent studies of G-protein-coupled receptor (GPCR) structures, it is not yet well understood how these receptors activate G proteins. The GPCR assay using baker’s yeast, Saccharomyces cerevisiae, is an effective experimental model for the characterization of GPCR-Gα interactions. Here, using the yeast endogenous Gα protein (Gpa1p) as template, we constructed various chimeric Gα proteins with a region that is considered to be necessary for interaction with mammalian receptors. The signaling assay using the yeast pheromone receptor revealed that the chimeric Gα protein harboring 37 gustducin-specific amino acid residues at its C-terminus (GPA1/gust37) maintained functionality in yeast. In contrast, GPA1/gust44, a variant routinely used in mammalian experimental systems, was not functional.
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  • Fumiya UNI, Sunmi LEE, Rie YATSUNAMI, Toshiaki FUKUI, Satoshi NAKAMURA
    2012 Volume 76 Issue 3 Pages 530-535
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Chitinase J from alkaliphilic Bacillus sp. J813 comprises a glycoside hydrolase (GH) family 18 catalytic domain (CatD), a fibronectin type III like domain, and a carbohydrate-binding module (CBM) family 5 chitin-binding domain (ChBD). It has been suggested that the ChBD binds to insoluble chitin and enhances its degradation by the CatD. To investigate the roles of two aromatic residues (Trp541 and Trp542), which are exposed on the surface of the ChBD, mutational analysis was performed. Single and double mutations of the two aromatic residues decreased binding and hydrolyzing abilities toward insoluble chitin. This result suggests that the ChBD binds to chitin by hydrophobic interactions via two surface-exposed aromatic residues. However, the double mutant, which has no such aromatic residue, bound to chitin at pH 5.2, probably by electrostatic interactions. Moreover, the ChBD bound to insoluble chitosan by electrostatic interactions.
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  • Cheol Kyu HWANG, Hong Sung CHUN
    2012 Volume 76 Issue 3 Pages 536-543
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Licorice (Glycyrrhiza uralensis) is a medicinal herb containing various bioactive components implicated in antioxidative, anti-inflammatory, antiviral, and neuroprotective effects, but the effects of licorice against Parkinson’s disease (PD)-related dopaminergic cell death have not been studied. In this study, we investigated the protective effects of isoliquiritigenin (ISL) isolated from Glycyrrhiza uralensis on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in a dopaminergic cell line, SN4741. ISL (1 μM) significantly attenuated 6-OHDA (50 μM)-induced reactive oxygen species (ROS) and nitric oxide (NO) generation and apoptotic cell death. ISL pretreatment effectively suppressed 6-OHDA-mediated upregulation of Bax, p-c-Jun N-terminal kinase (JNK), p-p38 mitogen-activated protein (MAP) kinase, cytochrome c release, and caspase 3 activation. In addition, ISL significantly attenuated 6-OHDA-induced Bcl-2, brain-derived neurotrophic factor (BDNF), and mitochondrial membrane potential (MMP) reduction. Pharmacological inhibitors of the phosphatidylinositol 3-kinase (PI3K)-Akt/protein kinase B (PKB) pathway reversed ISL-mediated neuroprotection against 6-OHDA toxicity in SN4741 cells. These results provide the first evidence that ISL can protect dopaminergic cells under oxidative stress conditions by regulating the apoptotic process.
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  • Yoshiaki SAWADA, Asami UMETSU, Yuki KOMATSU, Jun KITAMURA, Hiroyuki SU ...
    2012 Volume 76 Issue 3 Pages 544-550
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    DELLA proteins are negative regulators of the signaling of gibberellin (GA), a phytohormone regulating plant growth. DELLA degradation is triggered by its interaction with GID1, a soluble GA receptor, in the presence of bioactive GA. We isolated cDNA from a spliced variant of LsDELLA1 mRNA in lettuce, and named it LsDELLA1sv. It was deduced that LsDELLA1sv encodes truncated LsDELLA1, which has DELLA and VHYNP motifs at the N terminus but lacks part of the C-terminal GRAS domain. The recombinant LsDELLA1sv protein interacted with both Arabidopsis GID1 and lettuce GID1s in the presence of GA. A yeast two-hybrid assay suggested that LsDELLA1sv interacted with LsDELLA1. The ratio of LsDELLA1sv to LsDELLA1 transcripts was higher in flower samples at the late reproductive stage and seed samples (dry seeds and imbibed seeds) than in the other organ samples examined. This study suggests that LsDELLA1sv is a possible modulator of GA signaling in lettuce.
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  • Takahito CHIJIWA, Naoki IKEDA, Haruna MASUDA, Hiroaki HARA, Naoko ODA- ...
    2012 Volume 76 Issue 3 Pages 551-558
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
    JOURNALS FREE ACCESS
    Supplementary material
    A novel phospholipase A2 (PLA2) gene, named PfPLA 6, was found in a 6,328-bp NIS-1(5′)-a segment in the Protobothrops flavoviridis (Habu, Crotalinae) genome. A comparison of the aligned nucleotide sequences of Viperidae (Viperinae and Crotalinae) venom PLA2 genes, including PfPLA 6, revealed the deletion of a 12-bp segment called S1EX 1 and a 55-bp segment called S2EX 1 in exon 1 and the interposition of a 219-bp segment called SINT 2 (SINE) in intron 2. A classification of Viperidae PLA2 genes based on these structural modes indicated that the A-type genes (without SINE), including PfPLA 6, are evolutionarily ancestral to the B-type (Viperinae) and C-type (Crotalinae) PLA2 genes (both with SINE). Since PfPLA 6 is a pseudogene, an active prototype of PfPLA 6 can be assumed to be the ancestral PLA2 gene. Putative evolutionary processes from this A-type prototype PLA2 gene to descendent PLA2 genes are discussed.
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  • Asuka HAYASHI, Hiroki SAITOU, Tomomi MORI, Ikue MATANO, Hiroyuki SUGIS ...
    2012 Volume 76 Issue 3 Pages 559-566
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Monoacetylphloroglucinol (MAPG) acetyltransferase, catalyzing the conversion of MAPG to 2,4-diacetylphloroglucinol (DAPG), was purified from Pseudomonas sp. YGJ3 grown without Cl. Cl and pyoluteorin repressed expression of the enzyme. SDS-polyacrylamide gel electrophoresis showed that the purified enzyme (Mr=330 kDa) was composed of three subunits of 17, 38, and 43 kDa, and protein sequencing identified these as PhlB, PhlA, and PhlC respectively. The enzyme catalyzed the reversible disproportionation of 2 moles of MAPG to phloroglucinol (PG) and DAPG. The equilibrium constant K (=[DAPG][PG]/[MAPG]2) was estimated to be about 1.0 at 25 °C. A KpnI 20-kb DNA fragment was cloned from the genomic DNA of strain YGJ3, and a 12,598-bp long DNA region containing the phl gene cluster phlACBDEFGHI was sequenced. PCR cloning and expression of the phl genes in Escherichia coli confirmed that expression of phlACB genes produced MAPG ATase.
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  • Mayu ENYA, Keiko AOYAGI, Yoshihiro HISHIKAWA, Azusa YOSHIMURA, Koichi ...
    2012 Volume 76 Issue 3 Pages 567-574
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    The gene dad encoding 2,4′-dihydroxyacetophenone (DHAP) dioxygenase was cloned from Burkholderia sp. AZ11. The initiation codon GTG was converted to ATG for high-level expression of the enzyme in Escherichia coli. The enzyme was moderately thermostable, and the recombinant enzyme was briefly purified. The enzyme (Mr=90 kDa) was a homotetramer with a subunit Mr of 23 kDa. It contained 1.69 mol of non-heme iron, and had a dark gray color. On anaerobic incubation of it with DHAP, the absorption at around 400 nm increased due to the formation of an enzyme-DHAP complex. Multiple sequence alignment suggested that His77, His79, His115, and Glu96 in the cupin fold were possible metal ligands. The apparent Km for DHAP and the apparent Vmax were estimated to be 1.60 μM and 6.28 μmol/min/mg respectively. 2-Hydroxyacetophenone was a poor substrate. CuCl2 and HgCl2 strongly inhibited the enzyme, while FeSO4 weakly activated it.
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Biochemistry & Molecular Biology Notes
Food & Nutrition Science Regular Papers
  • Hatsue MORITAKA, Shin-ichi SAWAMURA, Makoto KOBAYASHI, Masami KITADE, ...
    2012 Volume 76 Issue 3 Pages 429-435
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    The relation between the rheological properties and the swallowing characteristics of vegetable juices fortified with 0–30.0% carrot puree (CP) was evaluated. The apparent viscosity of vegetable juices increased with increasing CP concentrations, and a increases in yield stress were observed at and above 17.5% CP. In a sensory evaluation, texture perceived in the oral cavity varied as between vegetable juices with >17.5% CP and those with <12.5% CP. The maximum velocity in the pharyngeal region was classified into three same-quality subgroups: vegetable juices with 0–12.5% CP, with 10.0–25.0% CP, and with 17.5–30.0% CP. It significantly decreased with increasing CP concentrations.
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  • Yumi TSURUTA, Koji NAGAO, Bungo SHIROUCHI, Saori NOMURA, Keisuke TSUGE ...
    2012 Volume 76 Issue 3 Pages 462-466
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Non-alcoholic fatty liver disease (NAFLD) is emerging as the most common liver disease in industrialized countries. The discovery of food components that would ameliorate NAFLD is therefore of interest. Lotus root, the edible rhizome of Nelumbo nucifera, contains a high level of polyphenolic compounds, and several health-promoting properties of lotus root have been reported. The present study examines whether dietary lotus root powder can protect db/db mice from hepatic injury. After 3 weeks of feeding, the hepatomegaly, hepatic triglyceride accumulation, and elevated hepatic injury markers in the serum were markedly alleviated in the Lotus diet-fed db/db mice relative to the control mice. These effects were partly attributable to suppression of the lipogenic enzyme activities and mRNA expression by the Lotus diet. The serum levels of adiponectin, which has been reported to have a protective effect against NAFLD, were significantly higher in the Lotus group than in the Control group of the db/db mice. Moreover, the hepatic expression of such inflammatory genes as tumor necrosis factor-alpha and monocyte chemoattractant protein-1 were markedly suppressed by the Lotus diet. We speculate that the development and progression of NAFLD were prevented by suppressing the expression of lipogenic and inflammatory genes as a result of the higher serum adioponectin level in the Lotus diet-fed db/db mice.
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  • Hiroki SUGIYAMA, Tomoaki HAGIWARA, Hisahiko WATANABE, Takaharu SAKIYAM ...
    2012 Volume 76 Issue 3 Pages 467-472
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    The surface fouling of food processing equipment by proteins was studied by investigating the adsorption of egg white proteins to the surface of stainless steel (SS) at pH 7.4 and 30 °C, and particularly the effects of different types of ionic substances. Ovalbumin and ovomucoid, acidic egg white proteins, were less adsorbed in the presence of phosphate (Pi), a multivalent anion, than in the presence of HEPES, an amphoteric ion. On the other hand, lysozyme, a basic egg white protein, was more adsorbed in the presence of Pi than in the presence of HEPES. Citrate as another multivalent anion and taurine as another amphoteric ion affected the respective adsorption of those egg white proteins similarly to Pi and HEPES. The adsorption of an egg white protein to an SS surface therefore depended on the combination of the type of protein and the effective charge of the coexisting ionic substance. This behaviour can be well explained by assuming that a small ionic substance precedes a protein in attaching to an SS surface, resulting in an alteration to the effective surface charge. Pretreating SS with a Pi buffer lowered the amount of ovalbumin adsorbed with the HEPES buffer, demonstrating that Pi can attach to and remain on the SS surface to affect the subsequent protein adsorption.
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  • Yasuhira IKEGAWA, So SATO, Garbeen LIM, Won HUR, Katsuhiro TANAKA, Mas ...
    2012 Volume 76 Issue 3 Pages 473-477
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    The efficacy of silk peptide in treatment of atopic dermatitis was examined in a picryl chloride-induced atopic dermatitis model in NC/Nga mice. Silk peptide ameliorated the development of atopic dermatitis by lowering the serum IgE concentration. Treatment of cultured spleen cells with silk peptide reduced IgE production by enhancing the production of IFN-γ and reducing the level of IL-4. The functional peptides in the silk peptide were identified as mixture of GAGA sequences containing peptides by mass spectrometry and in vitro assay. Our findings indicate that silk peptide exerts an effect on atopic dermatitis by modulating the Th1/Th2 balance.
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  • Yoshiyuki TATSUMI, Yoshimasa SASAHARA, Noriki KOHYAMA, Satomi AYANO, M ...
    2012 Volume 76 Issue 3 Pages 478-485
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    To reduce the immunogenicity of β-lactoglobulin (BLG), we prepared wild-type bovine BLG variant A (wt) and three site-specifically glycosylated BLGs (D28N, D137N/A139S, and P153A), and expressed them in the methylotrophic yeast Pichia pastoris by fusion of the cDNA to the sequence coding for the α-factor signal peptide from Saccharomyces cerevisiae. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE) analysis indicated that the glycosylated BLGs were conjugated with a ∼4 kDa high-mannose chain. Each glycosylated BLG retained ∼80% of the retinol-binding activity of BLG. Structural analyses by intrinsic fluorescence, CD spectra, and ELISA with monoclonal antibodies indicated that the surface structure was slightly changed by using protein engineering techniques, but that the site-specifically glycosylated BLGs were covered by high-mannose chains without substantial disruption of wt conformation. Antibody responses to the glycosylated BLGs tended to be weaker in BALB/c, C57BL/6, and C3H/He mice. We conclude that site-specific glycosylation is an effective method to reduce the immunogenicity of BLG, and that masking of epitopes by high-mannose chains is effective to reduce immunogenicity.
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  • Reiko MAEDA, Tomoaki IDA, Hideshi IHARA, Tatsuji SAKAMOTO
    2012 Volume 76 Issue 3 Pages 501-505
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Polysaccharides were extracted from Caulerpa lentillifera by treating with water and then purified by size-exclusion chromatography. The purified polysaccharides, termed SP1, were found to be sulfated xylogalactans with a molecular mass of more than 100 kDa. Adding SP1 to murine macrophage RAW 264.7 cells increased the production of nitric oxide (NO) in a dose-dependent manner. NO was found by immunoblotting and RT-PCR analyses to be synthesized by an inducible NO synthase. SP1 caused the degradation of IκB-α and the nuclear translocation of nuclear factor (NF)-κB subunit p65 in macrophage cells. SP1 also increased the phosphorylation of p38 mitogen-activated protein kinase (MAPK). These results demonstrate that SP1 activated macrophage cells via both the NF-κB and p38 MAPK signaling pathways. Moreover, SP1 increased the expression of various genes encoding cytokines, and the phagocytic activity of macrophage cells. These combined results show that SP1 immunostimulated the activity of macrophage cells.
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  • Sho ISHII, Mikiya KISHI, Keigo YAMAGAMI, Shinji OKADA, Keiko ABE, Taku ...
    2012 Volume 76 Issue 3 Pages 523-529
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Supplementary material
    Acetic acid induces unique physiological responses in mammalian cells. Our previous study found that fura-2-loaded human embryonic kidney (HEK) 293T cells showed a robust intracellular fluorescence response immediately after stimulation with acetic acid, and no such response in the case of citric acid. In the present study, we aimed to identify the unique characteristics of acetic acid responsible for this phenomenon. We found that one such feature is its hydrophobicity. We also discovered that acetic acid induces cell responses by intracellular acidification. Of the components of acetic acid in solution (protons, acetate ions, and undissociated acetic acid), undissociated acetic acid might be the functional unit that penetrates the lipid bilayer of cell membranes to acidify the intracellular environment, thereby inducing cell responses. The method used in this study might be convenient in evaluating the intracellular acidification of cultured cells by acids in the external environment.
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Food & Nutrition Science Notes
Food & Nutrition Science Communication
Microbiology & Fermentation Technology Regular Papers
  • Tomohiro KAINO, Yumi TASAKA, Yuki TATEHASHI, Hiroshi TAKAGI
    2012 Volume 76 Issue 3 Pages 454-461
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    γ-Glutamyl kinase (GK) is the rate-limiting enzyme in proline synthesis in microorganisms. Most microbial GKs contain an N-terminal kinase domain and a C-terminal pseudouridine synthase and archaeosine transglycosylase (PUA) domain. In contrast, higher eukaryotes possess a bifunctional Δ1-pyrroline-5-carboxylate synthetase, which consists of a PUA-free GK domain and a γ-glutamyl phosphate reductase (GPR) domain. Here, to examine the role of the C-terminal region, including the PUA domain of Saccharomyces cerevisiae GK, we constructed a variety of truncated yeast GK and GK/GPR fusion proteins from which the C-terminal region was deleted. A complementation test in Escherichia coli and S. cerevisiae and enzymatic analysis of recombinant proteins revealed that a 67-residue linker sequence between a 255-residue kinase domain and a 106-residue PUA domain is essential for GK activity. It also appeared that 67 or more residues of the C-terminal region, not the PUA domain itself, are required for the full display of GK activity. Further, the GK/GPR fusion protein was functional in E. coli, but decreased stability and Mg-binding ability as compared to wild-type GK. These results suggest that the C-terminal region of S. cerevisiae GK is involved in the folding and/or the stability of the kinase domain.
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  • Morio MIYAHARA, Sang-Wan KIM, Shengmin ZHOU, Shinya FUSHINOBU, Takeshi ...
    2012 Volume 76 Issue 3 Pages 495-500
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    The aerobic denitrifier Pseudomonas stutzeri TR2 (strain TR2) has the potential to reduce nitrous oxide emissions during the wastewater treatment process. In this application, it is important to find the best competitive survival conditions for strain TR2 in complex ecosystems. To that end, we examined co-cultures of strain TR2 with activated sludge via five passage cultures in a medium derived from treated piggery wastewater that contained a high concentration of ammonium. The results are as follows: (i) The medium supported the proliferation of strain TR2 (P. stutzeri strains) under denitrifying conditions. (ii) Nitrite was a better denitrification substrate than nitrate for TR2 survival. (iii) Strain TR2 also demonstrated strong survival even under aerobic conditions. This suggests that strain TR2 is effectively augmented to the wastewater treatment process, aiding in ammonium-nitrogen removal and reducing nitrous oxide production with a partial nitrification technique in which nitrite accumulates.
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  • Lanxiang HUANG, Arisa SHIZUME, Masahiro NOGAWA, Goro TAGUCHI, Makoto S ...
    2012 Volume 76 Issue 3 Pages 517-522
    Published: March 23, 2012
    Released: March 23, 2012
    [Advance publication] Released: March 07, 2012
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    Chitiniphilus shinanonensis strain SAY3T is a chitinolytic bacterium isolated from moat water of Ueda Castle in Nagano Prefecture, Japan. Fifteen genes encoding putative chitinolytic enzymes (chiA-chiO) have been isolated from this bacterium. Five of these constitute a single operon (chiCDEFG). The open reading frames of chiC, chiD, chiE, and chiG show sequence similarity to family 18 chitinases, while chiF encodes a polypeptide with two chitin-binding domains but no catalytic domain. Each of the five genes was successfully expressed in Escherichia coli, and the resulting recombinant proteins were characterized. Four of the recombinant proteins (ChiC, ChiD, ChiE, and ChiG) exhibited endo-type chitinase activity toward chitinous substrates, while ChiF showed no chitinolytic activity. In contrast to most endo-type chitinases, which mainly produce a dimer of N-acetyl-D-glucosamine (GlcNAc) as final product, ChiG completely split the GlcNAc dimer into GlcNAc monomers, indicating that it is a novel chitinase.
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Microbiology & Fermentation Technology Notes
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