論文 - 冨田　勝

A Yeast Metabolite Extraction Protocol Optimised for Time-Series Analyses

Sasidharan, K., Soga, T., Tomita, M. and Murray, D., B.

PLoS ONE （PLoS ONE）  7 （ 8 ） e44283 2012年

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

There is an increasing call for the absolute quantification of time-resolved metabolite data. However, a number of technical issues exist, such as metabolites being modified/degraded either chemically or enzymatically during the extraction process. Additionally, capillary electrophoresis mass spectrometry (CE-MS) is incompatible with high salt concentrations often used in extraction protocols. In microbial systems, metabolite yield is influenced by the extraction protocol used and the cell disruption rate. Here we present a method that rapidly quenches metabolism using dry-ice ethanol bath and methanol N-ethylmaleimide solution (thus stabilising thiols), disrupts cells efficiently using bead-beating and avoids artefacts created by live-cell pelleting. Rapid sample processing minimised metabolite leaching. Cell weight, number and size distribution was used to calculate metabolites to an attomol/cell level. We apply this method to samples obtained from the respiratory oscillation that occurs when yeast are grown continuously. © 2012 Sasidharan et al.

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Metabolic regulation analysis of wild-type and arcA mutant Escherichia coli under nitrate conditions using different levels of omics data

Toya, Y., Nakahigashi, K., Tomita, M., and Shimizu, K.

Molecular BioSystems （Molecular BioSystems）  8 （ 10 ） 2593-604. - 2604 2012年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  1742206X

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It is of practical interest to investigate the effect of nitrates on bacterial metabolic regulation of both fermentation and energy generation, as compared to aerobic and anaerobic growth without nitrates. Although gene level regulation has previously been studied for nitrate assimilation, it is important to understand this metabolic regulation in terms of global regulators. In the present study, therefore, we measured gene expression using DNA microarrays, intracellular metabolite concentrations using CE-TOFMS, and metabolic fluxes using the ¹³C-labeling technique for wild-type E. coli and the ΔarcA (a global regulatory gene for anoxic response control, ArcA) mutant to compare the metabolic state under nitrate conditions to that under aerobic and anaerobic conditions without nitrates in continuous culture conditions at a dilution rate of 0.2 h^-1. In wild-type, although the measured metabolite concentrations changed very little among the three culture conditions, the TCA cycle and the pentose phosphate pathway fluxes were significantly different under each condition. These results suggested that the ATP production rate was 29% higher under nitrate conditions than that under anaerobic conditions, whereas the ATP production rate was 10% lower than that under aerobic conditions. The flux changes in the TCA cycle were caused by changes in control at the gene expression level. In ΔarcA mutant, the TCA cycle flux was significantly increased (4.4 times higher than that of the wild type) under nitrate conditions. Similarly, the intracellular ATP/ADP ratio increased approximately two-fold compared to that of the wild-type strain. © 2012 The Royal Society of Chemistry.

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Temporal profiling of lapatinib-suppressed phosphorylation signals in EGFR/HER2 pathways

Imami K., Sugiyama N., Imamura H., Wakabayashi M., Tomita M., Taniguchi M., Ueno T., Toi M., Ishihama Y.

Molecular and Cellular Proteomics （Molecular and Cellular Proteomics）  11 （ 12 ） [Epub ahead of print] - 1757 2012年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  15359476

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Lapatinib is a clinically potent kinase inhibitor for breast cancer patients because of its outstanding selectivity for epidermal growth factor receptor (EGFR) and EGFR2 (also known as HER2). However, there is only limited information about the in vivo effects of lapatinib on EGFR/HER2 and downstream signaling targets. Here, we profiled the lapatinib-induced time- and dose-dependent phosphorylation dynamics in SKBR3 breast cancer cells by means of quantitative phosphoproteomics. Among 4953 identified phosphopeptides from 1548 proteins, a small proportion (5-7%) was regulated at least twofold by 1-10 μM lapatinib. We obtained a comprehensive phosphorylation map of 21 sites on EGFR/HER2, including nine novel sites on HER2. Among them, serine/threonine phosphosites located in a small region of HER2 (amino acid residues 1049-1083) were up-regulated by the drug, whereas all other sites were down-regulated. We show that cAMP-dependent protein kinase is involved in phosphorylation of this particular region of HER2 and regulates HER2 tyrosine kinase activity. Computational analyses of quantitative phosphoproteome data indicated for the first time that protein-protein networks related to cytoskeletal organization and transcriptional/translational regulation, such as RNP complexes (i.e. hnRNP, snRNP, telomerase, ribosome), are linked to EGFR/HER2 signaling networks. To our knowledge, this is the first report to profile the temporal response of phosphorylation dynamics to a kinase inhibitor. The results provide new insights into EGFR/HER2 regulation through region-specific phosphorylation, as well as a global view of the cellular signaling networks associated with the anti-breast cancer action of lapatinib. © 2012 by The American Society for Biochemistry and Molecular Biology, Inc.

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Sheathless capillary electrophoresis-mass spectrometry with a high-sensitivity porous sprayer for cationic metabolome analysis

Hirayama A., Tomita M., Soga T.

Analyst （Analyst）  137 （ 21 ） 5026-5033 - 5033 2012年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  00032654

　概要を見る

Sheath-flow capillary electrophoresis-mass spectrometry (CE-MS) has emerged as a new tool for comprehensive analysis of charged metabolites. However, it needs to be more sensitive. Here, we report a sheathless capillary electrophoresis-electrospray ionization-mass spectrometry method for cationic metabolome analysis. This system used a high-sensitivity porous sprayer interface and 10% (v/v) acetic acid as the background electrolyte (BGE). Under optimized conditions, 53 cationic metabolites, including amino acids and their derivatives, amines, nucleic acids and small peptides, were successfully separated and selectively detected with a time-of-flight mass spectrometer. At a signal-to-noise ratio of three, the concentration detection limits for these compounds were between 0.004 and 0.8 μmol L-1 (amount detection limit, 0.01 to 2 fmol) with pressure injection at 20.7 kPa for 5 s (2.6 nL). Compared with conventional sheath-flow CE-MS, the detection limit of the present method was increased more than 5-fold for 21 (40%) of the compounds detected. When the method was applied to the analysis of cationic metabolites obtained from human urine, there was a 10-fold increase in the number of detected peaks compared with conventional methods. More than 180 successive runs could be conducted without any problems, and only the BGE needed to be changed. © 2012 The Royal Society of Chemistry.

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Pilot study of changes in salivary metabolic profiles induced by template therapy

Tanaka S., Taga H., Maehara K., Kaneshima A., Machino M., Onuma H., Kaneko M., Sakagami H., Sugimoto M., Soga T., Tomita M.

In Vivo （In Vivo）  26 （ 6 ） 1015-1020 - 1020 2012年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0258851X

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Background: Occlusal raising method (so-called 'Template therapy') has been reported to alleviate various diseases and symptoms, but the underlying mechanism is not clear. We searched the low-molecular weight metabolite(s) in the saliva, the concentration of which is significantly changed by the template therapy. Materials and Methods: One female patient with headache underwent the template therapy for 12 days, and her total saliva was subjected to non-targeted analysis using capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS). Results: One hundred and thirteen substances were identified in the saliva. Glycine was the most abundant amino acid in the saliva, followed by alanine, serine and proline. After the start of the template therapy, her headache was alleviated, accompanied by a significant (p=0.042) increase of salivary concentration of glycine, as compared with total amino acids whereas that of other amino acids was not significantly changed. In the metabolomics profile, salivary concentration of large number of metabolites as compared with total metabolite concentration decreased, including N-acetylneuraminate (p=0.025) and p-hydroxyphenylacetate (p=0.039). Conclusion: This pilot study demonstrated, to our knowledge for the first time, that only glycine exhibited unique changes among total metabolites, suggesting its significant role in template therapy.

Is central dogma a global property of cellular information flow?

Piras V., Tomita M., Selvarajoo K.

Frontiers in Physiology （Frontiers in Physiology）  3   439 2012年

研究論文（学術雑誌）, 共著, 査読有り

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The central dogma of molecular biology has come under scrutiny in recent years. Here, we reviewed high-throughput mRNA and protein expression data of Escherichia coli, Saccharomyces cerevisiae, and several mammalian cells. At both single cell and population scales, the statistical comparisons between the entire transcriptomes and proteomes show clear correlation structures. In contrast, the pair-wise correlations of single transcripts to proteins show nullity. These data suggest that the organizing structure guiding cellular processes is observed at omics-wide scale, and not at single molecule level. The central dogma, thus, globally emerges as an average integrated flow of cellular information. © 2012 Piras, Tomita and Selvarajoo.

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Metabolomics: A New Omics Technology for Traditional Herbal Medicine Analysis

Iino, K., Sugimoto, M., Soga, T. and Tomita, M.

Chinese Medicine: Acupuncture, Herbal Medicine and Therapies    45-55 2012年

研究論文（学術雑誌）, 共著, 査読有り

Metabolic profiling reveals new serum biomarkers for differentiating diabetic nephropathy

Hirayama A., Nakashima E., Sugimoto M., Akiyama S.I., Sato W., Maruyama S., Matsuo S., Tomita M., Yuzawa Y., Soga T.

Analytical and Bioanalytical Chemistry （Analytical and Bioanalytical Chemistry）  404 （ 10 ） 3101-9 - 3109 2012年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  16182642

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Capillary electrophoresis coupled with time-offlight mass spectrometry was used to explore new serum biomarkers with high sensitivity and specificity for diabetic nephropathy (DN) diagnosis, through comprehensive analysis of serum metabolites with 78 diabetic patients. Multivariate analyses were used for identification of marker candidates and development of discriminative models. Of the 289 profiled metabolites, orthogonal partial leastsquares discriminant analysis identified 19 metabolites that could distinguish between DN with macroalbuminuria and diabetic patients without albuminuria. These identified metabolites included creatinine, aspartic acid, γ-butyrobetaine, citrulline, symmetric dimethylarginine (SDMA), kynurenine, azelaic acid, and galactaric acid. Significant correlations between all these metabolites and urinary albumin-to-creatinine ratios (p<0.009, Spearman's rank test) were observed. When five metabolites (including γ-butyrobetaine, SDMA, azelaic acid and two unknowns) were selected from 19 metabolites and applied for multiple logistic regressionmodel, AUC value for diagnosing DN was 0.927 using the whole dataset, and 0.880 in a cross-validation test. In addition, when four known metabolites (aspartic acid, SDMA, azelaic acid and galactaric acid) were applied, the resulting AUC was still high at 0.844 with the whole dataset and 0.792 with cross-validation. Combination of serum metabolomics with multivariate analyses enabled accurate discrimination of DN patients. The results suggest that capillary electrophoresis-mass spectrometry based metabolome analysis could be used for DN diagnosis. © Springer-Verlag 2012.

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A simple method to provide a shuttling plasmid for delivery to other host ascertained by prolonged stability of extracellular plasmid DNA released from Escherichia coli K12 endA mutant, deficient in major endonuclease

Itaya M., Kawata Y., Sato M., Tomita M., Nakahigashi K.

Journal of Biochemistry （Journal of Biochemistry）  152 （ 6 ） 501–504 - 504 2012年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0021924X

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Escherichia coli lyses by lambda phage propagation. Circular plasmid DNA was present during E. coli lysis as an extracellular plasmid DNA (excpDNA) that was stable enough to transform coexisting competent Bacillus subtilis cells. Detailed investigations unveiled that excpDNA is transient in both quality and quantity, with stability lasting no more than several hours. A survey using E. coli lambda lysogens with various genetic backgrounds demonstrated that the loss of Endonuclease I (ΔendA::kan) conferred extraordinary stability upon excpDNA for as long as 48 h. Studies on endA mutants suggested that excpDNA remained localized in cell debris, in contrast to E. coli genome DNA, which diffused into medium at an early point in lysis. Lambda lysogens constructed on endA recA mutants are presented for potential pipelines in delivery to other competent proficient microbes. © 2012 The Authors.

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A medium-chain fatty acid as an alternative energy source in mouse preimplantation development

Yamada M., Takanashi K., Hamatani T., Hirayama A., Akutsu H., Fukunaga T., Ogawa S., Sugawara K., Shinoda K., Soga T., Umezawa A., Kuji N., Yoshimura Y., Tomita M.

Scientific Reports （Scientific Reports）  2   930 2012年

研究論文（学術雑誌）, 共著, 査読有り

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To further optimize the culturing of preimplantation embryos, we undertook metabolomic analysis of relevant culture media using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). We detected 28 metabolites: 23 embryo-excreted metabolites including 16 amino acids and 5 media-derived metabolites (e.g., octanoate, a medium-chain fatty acid (MCFA)). Due to the lack of information on MCFAs in mammalian preimplantation development, this study examined octanoate as a potential alternative energy source for preimplantation embryo cultures. No embryos survived in culture media lacking FAs, pyruvate, and glucose, but supplementation of octanoate rescued the embryonic development. Immunoblotting showed significant expression of acyl-CoA dehydrogenase and hydroxyacyl-CoA dehydrogenase, important enzymes for β-oxidation of MCFAs, in preimplantation embryo. Furthermore, CE-TOFMS traced [1-13 C 8[ octanoate added to the culture media into intermediate metabolites of the TCA cycle via β-oxidation in mitochondria. These results are the first demonstration that octanoate could provide an efficient alternative energy source throughout preimplantation development.

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Light Microscopy and Phylogenetic Analyses of Chlamydomonas Species (Volvocales, Chlorophyceae). : I. Chlamydomonas pseudomacrostigma and Chlamydomonas media

Nakada, T., Nozaki, H. and Tomita, M.

Acta phytotaxonomica et geobotanica 62:69-78 62   69 - 78 2012年

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Serial assembly of Thermus megaplasmid DNA in the genome of Bacillus subtilis 168: A BAC-based domino method applied to DNA with a high GC content

Ohtani N., Hasegawa M., Sato M., Tomita M., Kaneko S., Itaya M.

Biotechnology Journal （Biotechnology Journal）  7 （ 7 ） 867 - 76 2012年

共著, 査読有り,  ISSN  18606768

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Bacillus subtilis is the only bacterium-based host able to clone giant DNA above 1000 kbp. DNA previously handled by this host was limited to that with GC content similar to or lower than that of the B. subtilis genome. To expand the target DNA range to higher GC content, we tried to clone a pTT27 megaplasmid (257 kbp, 69% of G+C) from Thermus thermophilus. To facilitate the reconstruction process, we subcloned pTT27 in a bacterial artificial chromosome (BAC) vector of Escherichia coli. Owing to the ability of BAC to carry around 100 kbp DNA, only 4 clones were needed to cover the pTT27 and conduct step-by-step assembly in the B. subtilis genome. The full length of 257 kbp was reconstructed through 3 intermediary lengths (108, 153, and 226 kbp), despite an unexpected difficulty in the maintenance of DNA >200 kbp. Retrieval of these four pTT27 segments from the B. subtilis genome by genetic transfer to a plasmid pLS20 was attempted. A stable plasmid clone was obtained only for the 108 and 153 kbp intermediates. The B. subtilis genome was demonstrated to accommodate large DNA with a high GC content, but may be restricted to less than 200 kbp by unidentified mechanisms. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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Computational assessment of insulin secretion and insulin sensitivity from 2-h oral glucose tolerance tests for clinical use for type 2 diabetes

Seike, Masayoshi; Saitou, Takeo; Kouchi, Yasuhiro; Ohara, Takeshi; Matsuhisa, Munehide; Sakaguchi, Kazuhiko; Tomita, Koji; Kosugi, Keisuke; Kashiwagi, Atsunori; Kasuga, Masato; Tomita, Masaru; Naito, Yasuhiro; Nakajima, Hiromu

Journal of Physiological Sciences （Journal of Physiological Sciences）  61 （ 4 ） 321-330 - 330 2011年07月

研究論文（学術雑誌）, 共著,  ISSN  18806546

　概要を見る

In type 2 diabetes mellitus, glucose homeostasis is tightly maintained through insulin secretion and insulin sensitivity. Therefore, finding an accurate method to assess insulin secretion and sensitivity using clinically available data would enhance the quality of diabetic medical care. In an effort to find such a method, we developed a computational approach to derive indices of these factors using a 2-h oral glucose tolerance test (OGTT). To evaluate our method, clinical data from subjects who received an OGTT and a glucose clamp test were examined. Our insulin secretion index was significantly correlated with an analogous index obtained from a hyperglycemic clamp test (r = 0.90, n = 46, p < 0.001). Our insulin sensitivity index sensitivity was also significantly correlated with an analogous index obtained from a hyperinsulinemic-euglycemic clamp test (r = 0.56, n = 79, p < 0.001). These results suggest that our method can potentially provide an accurate and convenient tool toward improving the management of diabetes in clinical practice by assessing insulin secretion and insulin sensitivity. © 2011 The Author(s).

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A novel mechanism regulates H2S and SO2 production in Saccharomyces cerevisiae

Yoshida S., Imoto J., Minato T., Oouchi R., Kamada Y., Tomita M., Soga T., Yoshimoto H.

Yeast 28 （ 2 ） 109 - 121 2011年02月

ISSN  0749503X

　概要を見る

Sulfite (SO2) plays an important role in flavour stability in alcoholic beverages, whereas hydrogen sulfide (H2S) has an undesirable aroma. To discover the cellular processes that control SO2 and H2S production, we screened a library of Saccharomyces cerevisiae deletion mutants. Deletion of 12 genes led to increased H2S productivity. Ten of these genes are known to be involved in sulfur-containing amino acid metabolism, whereas UBI4 functions in the ubiquitin-proteasome system and SKP2 encodes an F-box-containing protein whose function is unknown. We found that the skp2 mutant accumulated H2S and SO2, because the adenosylphophosulfate kinase Met14p is a substrate of SCFSkp2 and more stable in the skp2 mutant than in the wild-type strain. Furthermore, the skp2 mutant grew more slowly than the wild-type strain under nutrient-limited conditions. Metabolome analysis showed that the concentration of intracellular cysteine is lower in the skp2 mutant than in the wild-type strain. The slow growth of the skp2 mutant was due to a lower concentration of intracellular cysteine, because the addition of cysteine suppressed the slow growth. In the skp2 mutant, the cysteine biosynthesis proteins Str2p, Str3p and Str4p are more stable than in the wild-type strain. Moreover, supplementation with methionine, S-adenosylmethionine, S-adenosylhomocysteine and homocysteine also suppressed the slow growth. Overexpression of STR1 or STR4 caused a more severe defect in the skp2 mutant. These results suggest that the balance of methionine and cysteine biosynthesis is important for yeast cell growth. Thus, Skp2p is one of the key components regulating this balance and H2S/SO2 production. © 2010 John Wiley & Sons, Ltd.

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A novel three-unit tRNA splicing endonuclease found in ultrasmall Archaea possesses broad substrate specificity

Fujishima K., Sugahara J., Miller C.S., Baker B.J., Di Giulio M., Takesue K., Sato A., Tomita M., Banfield J.F., Kanai A.

Nucleic Acids Research （Nucleic Acids Research）  39 （ 22 ） 9695-9704 - 9704 2011年

研究論文（学術雑誌）, 共著,  ISSN  03051048

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tRNA splicing endonucleases, essential enzymes found in Archaea and Eukaryotes, are involved in the processing of pre-tRNA molecules. In Archaea, three types of splicing endonuclease [homotetrameric: α4, homodimeric: α2, and heterotetrameric: (αβ)2] have been identified, each representing different substrate specificity during the tRNA intron cleavage. Here, we discovered a fourth type of archaeal tRNA splicing endonuclease (2) in the genome of the acidophilic archaeon Candidatus Micrarchaeum acidiphilum, referred to as ARMAN-2 and its closely related species, ARMAN-1. The enzyme consists of two duplicated catalytic units and one structural unit encoded on a single gene, representing a novel three-unit architecture. Homodimeric formation was confirmed by cross-linking assay, and site-directed mutagenesis determined that the conserved L10-pocket interaction between catalytic and structural unit is necessary for the assembly. A tRNA splicing assay reveal that 2 endonuclease cleaves both canonical and non-canonical bulge-helix-bulge motifs, similar to that of (αβ)2 endonuclease. Unlike other ARMAN and Euryarchaeota, tRNAs found in ARMAN-2 are highly disrupted by introns at various positions, which again resemble the properties of archaeal species with (αβ)2 endonuclease. Thus, the discovery of 2 endonuclease in an archaeon deeply branched within Euryarchaeota represents a new example of the coevolution of tRNA and their processing enzymes. © The Author(s) 2011. Published by Oxford University Press.

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Comprehensive prediction of chromosome dimer resolution sites in bacterial genomes

Kono N., Arakawa K., Tomita M.

BMC Genomics （BMC Genomics）  12   19 2011年

研究論文（学術雑誌）, 共著, 査読有り

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Background: During the replication process of bacteria with circular chromosomes, an odd number of homologous recombination events results in concatenated dimer chromosomes that cannot be partitioned into daughter cells. However, many bacteria harbor a conserved dimer resolution machinery consisting of one or two tyrosine recombinases, XerC and XerD, and their 28-bp target site, dif.Results: To study the evolution of the dif/XerCD system and its relationship with replication termination, we report the comprehensive prediction of dif sequences in silico using a phylogenetic prediction approach based on iterated hidden Markov modeling. Using this method, dif sites were identified in 641 organisms among 16 phyla, with a 97.64% identification rate for single-chromosome strains. The dif sequence positions were shown to be strongly correlated with the GC skew shift-point that is induced by replicational mutation/selection pressures, but the difference in the positions of the predicted dif sites and the GC skew shift-points did not correlate with the degree of replicational mutation/selection pressures.Conclusions: The sequence of dif sites is widely conserved among many bacterial phyla, and they can be computationally identified using our method. The lack of correlation between dif position and the degree of GC skew suggests that replication termination does not occur strictly at dif sites. © 2011 Kono et al; licensee BioMed Central Ltd.

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Integrative features of the yeast phosphoproteome and protein-protein interaction map

Yachie N., Saito R., Sugiyama N., Tomita M., Ishihama Y.

PLoS Computational Biology （PLoS Computational Biology）  7 （ 1 ） e1001064 2011年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  1553734X

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Following recent advances in high-throughput mass spectrometry (MS)-based proteomics, the numbers of identified phosphoproteins and their phosphosites have greatly increased in a wide variety of organisms. Although a critical role of phosphorylation is control of protein signaling, our understanding of the phosphoproteome remains limited. Here, we report unexpected, large-scale connections revealed between the phosphoproteome and protein interactome by integrative data-mining of yeast multi-omics data. First, new phosphoproteome data on yeast cells were obtained by MSbased proteomics and unified with publicly available yeast phosphoproteome data. This revealed that nearly 60% of,6,000 yeast genes encode phosphoproteins. We mapped these unified phosphoproteome data on a yeast protein-protein interaction (PPI) network with other yeast multi-omics datasets containing information about proteome abundance, proteome disorders, literature-derived signaling reactomes, and in vitro substratomes of kinases. In the phospho-PPI, phosphoproteins had more interacting partners than nonphosphoproteins, implying that a large fraction of intracellular protein interaction patterns (including those of protein complex formation) is affected by reversible and alternative phosphorylation reactions. Although highly abundant or unstructured proteins have a high chance of both interacting with other proteins and being phosphorylated within cells, the difference between the number counts of interacting partners of phosphoproteins and nonphosphoproteins was significant independently of protein abundance and disorder level. Moreover, analysis of the phospho-PPI and yeast signaling reactome data suggested that co-phosphorylation of interacting proteins by single kinases is common within cells. These multi-omics analyses illuminate how wide-ranging intracellular phosphorylation events and the diversity of physical protein interactions are largely affected by each other. © 2011 Yachie et al.

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Computational analysis suggests a highly bendable, fragile structure for nucleosomal DNA

Nozaki T., Yachie N., Ogawa R., Saito R., Tomita M.

Gene （Gene）  476 （ 1-2 ） 10-14 - 14 2011年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  03781119

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Eukaryotic chromosomal DNA coils around histones to form nucleosomes. Although histone affinity for DNA depends on DNA sequence patterns, how nucleosome positioning is determined by them remains unknown. Here, we show relationships between nucleosome positioning and two structural characteristics of DNA conferred by DNA sequence. Analysis of bendability and hydroxyl radical cleavage intensity of nucleosomal DNA sequences indicated that nucleosomal DNA is bendable and fragile and that nucleosome positional stability was correlated with characteristics of DNA. This result explains how histone positioning is partially determined by nucleosomal DNA structure, illuminating the optimization of chromosomal DNA packaging that controls cellular dynamics. © 2011 Elsevier B.V.

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Metabolomic anatomy of an animal model revealing homeostatic imbalances in dyslipidaemia

Ooga, Takushi ; Sato, Hajime ; Nagashima, Atsushi ; Sasaki, Kazunori ; Tomita, Masaru ; Soga, Tomoyoshi ; Ohashi, Yoshiaki

Molecular BioSystems （Molecular BioSystems）  7 （ 4 ） 1217-1223 - 1223 2011年

研究論文（学術雑誌）, 共著,  ISSN  1742-206X

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Metabolomics is an emerging technology that reveals homeostatic imbalances in biological systems. Global determination of metabolite concentrations in body fluid and tissues provides novel anatomical aspects of pathological conditions that cannot be obtained from target-specific measurements. Here, we characterised metabolic imbalance in Watanabe heritable hyperlipidaemic rabbits as a model of hypercholesterolaemia. Using a mass spectrometry-based system, we measured a total of 335 metabolites in plasma and tissues (liver, aorta, cardiac muscle, and brain) from WHHL and healthy control rabbits. From the comparison between two metabolomic profiles, pathophysiological features including glutathione and phosphatidylcholine metabolism indicated the occurrence of oxidative stress in several tissues. Especially for the liver, imbalanced purine catabolism shed light on the transcriptional activation of xanthine oxidase, which is thought to act in absorbing or possibly triggering oxidative stress. We also applied this system to assess the therapeutic effects of simvastatin administration. After the treatment, a portion of the metabolomic features in pathological conditions showed alterations suggesting restoration of metabolism to the healthy condition. These changes were considered to be due to the pleiotropic action of statin, including antioxidant effects, rather than its main inhibitory action on cholesterol biosynthesis. © The Royal Society of Chemistry.

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OryzaPG-DB: Rice Proteome Database based on Shotgun Proteogenomics

Helmy M., Tomita M., Ishihama Y.

BMC Plant Biology （BMC Plant Biology）  11   63 2011年

研究論文（学術雑誌）, 共著, 査読有り

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Background: Proteogenomics aims to utilize experimental proteome information for refinement of genome annotation. Since mass spectrometry-based shotgun proteomics approaches provide large-scale peptide sequencing data with high throughput, a data repository for shotgun proteogenomics would represent a valuable source of gene expression evidence at the translational level for genome re-annotation.Description: Here, we present OryzaPG-DB, a rice proteome database based on shotgun proteogenomics, which incorporates the genomic features of experimental shotgun proteomics data. This version of the database was created from the results of 27 nanoLC-MS/MS runs on a hybrid ion trap-orbitrap mass spectrometer, which offers high accuracy for analyzing tryptic digests from undifferentiated cultured rice cells. Peptides were identified by searching the product ion spectra against the protein, cDNA, transcript and genome databases from Michigan State University, and were mapped to the rice genome. Approximately 3200 genes were covered by these peptides and 40 of them contained novel genomic features. Users can search, download or navigate the database per chromosome, gene, protein, cDNA or transcript and download the updated annotations in standard GFF3 format, with visualization in PNG format. In addition, the database scheme of OryzaPG was designed to be generic and can be reused to host similar proteogenomic information for other species. OryzaPG is the first proteogenomics-based database of the rice proteome, providing peptide-based expression profiles, together with the corresponding genomic origin, including the annotation of novelty for each peptide.Conclusions: The OryzaPG database was constructed and is freely available at http://oryzapg.iab.keio.ac.jp/. © 2011 Helmy et al; licensee BioMed Central Ltd.

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