Hideaki Yukawa

Research Institute of Innovative Technology for the Earth, Kioto, Kyōto, Japan

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Publications (195)582.49 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The transcriptional regulator GntR1 downregultates the genes for gluconate catabolism and pentose phosphate pathway in Corynebacterium glutamicum. Gluconate lowers the DNA binding affinity of GntR1, which is probably the mechanism of gluconate-dependent induction of these genes. In addition, GntR1 positively regulates the ptsG, a gene encoding for a major glucose transporter, and the pck, a gene encoding phosphoenolpyruvate carboxykinase. Here, we searched for the new target of GntR1 at genome-wide scale by chromatin immunoprecipitation in conjunction with microarray (ChIP-chip) analysis. This analysis identified 56 in vivo GntR1 binding sites, of which 7 sites were previously reported. The newly identified GntR1 sites include the upstream regions of carbon metabolism genes such as pyk, maeB, gapB, and icd, encoding for pyruvate kinase, malic enzyme, glyceraldehyde 3-phosphate dehydrogenase B, and isocitrate dehydrogenase, respectively. Binding of GntR1 to the promoter region of these genes was confirmed by electrophoretic mobility shift assay. The activity of the icd, gapB, and maeB promoters was reduced by the mutation at GntR1 binding site in contrast to the pyk promoter activity increased, indicating that GntR1 is a transcriptional activator of icd, gapB, and maeB and is a repressor of pyk. Thus, it is likely that GntR1 stimulates glucose uptake by inducing the phosphoenolpyruvate (PEP): carbohydrate phosphotransferase system (PTS) gene while repressing pyk to increase PEP availability in the absence of gluconate. Repression of zwf and gnd may reduce NADPH supply which may be compensated by the induction of maeB, and icd. Upregulation of icd, gapB, and maeB and downregulation of pyk by GntR1 probably support gluconeogenesis.
    Journal of bacteriology. 06/2014;
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    ABSTRACT: The Corynebacterium glutamicum ATCC 31831 araBDA operon consists of three L-arabinose catabolic genes, upstream of which galM, araR, and araE genes are located in opposite orientation. araR encodes a LacI-type transcriptional regulator that negatively regulates the L-arabinose-inducible expression of araBDA and araE (encoding an L-arabionose transporter) through a mechanism yet to be identified. Here, we show that AraR protein binds in vitro to three sites, one upstream of araBDA and two upstream of araE. We verify that a 16-bp consensus palindromic sequence is essential in binding of AraR using a series of mutations introduced upstream of araB used in electrophoretic mobility shift assays. Moreover, the DNA binding activity of AraR is reduced by L-arabinose. We employ quantitative RT-PCR analyses using various mutant strains deficient in L-arabinose utilization genes to demonstrate that the prominent upregulation of araBDA and araE within 5 min of L-arabinose supplementation is dependent on the uptake but independent of the catabolism of L-arabinose. Similar expression patterns, together with the upregulation by araR disruption without L-arabinose, are evident with the apparent galM-araR operon, although attendant changes in expression levels are much smaller than those realized with the expression of araBDA and araE. The AraR-binding site upstream of araB overlaps the -10 region of the divergent galM promoter. These observations indicate that AraR acts as a transcriptional repressor of araBDA, araE, and galM-araR, and that L-arabinose acts as an intracellular negative effector of the AraR-dependent regulation.
    Journal of bacteriology 04/2014; · 3.94 Impact Factor
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    ABSTRACT: The qsu operon of Corynebacterium glutamicum comprises four genes (qsuABCD) that underpin the microorganism's quinate/shikimate utilization pathways. The genes encode enzymes that catalyse reactions at the metabolic branch point between the biosynthesis route for synthesis of aromatic compounds and the catabolic route for degradation of quinate and shikimate for energy production. A qsuR gene located immediately upstream of qsuA encodes a protein (QsuR) which activates the operon in the presence of quinate or shikimate. Three observations support chorismate, an intermediate of the biosynthesis route, as a direct effector of QsuR: First, induction of qsuA mRNA in the presence of either quinate or shikimate disappears upon deletion of the gene encoding chorismate synthase. Second, chorismate accumulates when the operon is induced. Third, a DNase I-protected segment by QsuR is shortened in the presence of chorismate. The QsuR tetramer senses the accumulation of chorismate and activates qsu genes that promote the quinate/shikimate catabolic instead of the aromatic compounds biosynthetic route. Such chorismate-dependent control of carbon flow has not been previously described.
    Molecular Microbiology 02/2014; · 4.96 Impact Factor
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    ABSTRACT: Riboflavin is a precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which work as cofactors of numerous enzymes. Understanding the supply system of these cofactors in bacteria, particularly those used for industrial production of value added chemicals, is important given the pivotal role the cofactors play in substrate metabolism. In this work, we examined the effect of disruption of riboflavin utilization genes on cell growth, cytoplasmic flavin levels, and expression of riboflavin transporter in Corynebacterium glutamicum. Disruption of the ribA gene that encodes bifunctional GTP cyclohydrolase II/3,4-dihydroxy-2-butanone 4-phosphate synthase in C. glutamicum suppressed growth in the absence of supplemental riboflavin. The growth was fully recovered upon supplementation with 1 μM riboflavin, albeit at reduced intracellular concentrations of FMN and FAD during the log phase. Concomitant disruption of the ribA and ribM gene that encodes a riboflavin transporter exacerbated supplemental riboflavin requirement from 1 μM to 50 μM. RibM expression in FMN-rich cells was about 100-fold lower than that in FMN-limited cells. Mutations in putative FMN-riboswitch present immediately upstream of the ribM gene abolished the FMN response. This 5'UTR sequence of ribM constitutes a functional FMN-riboswitch in C. glutamicum.
    Applied Microbiology and Biotechnology 02/2014; · 3.69 Impact Factor
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    ABSTRACT: Corynebacterium glutamicum ArnR is a novel transcriptional regulator that represses expression of the nitrate reductase operon narKGHJI and the NO-detoxifying flavohemoglobin gene hmp under aerobic conditions. In a previous study we showed that the ArnR-mediated repression is relieved during anaerobic nitrate respiration but could not pinpoint the specific signal that ArnR senses. In this study, we show that in the absence of nitrate, the ArnR-mediated repression is maintained under anaerobic conditions. The derepression in response to nitrate is eliminated by disruption of narG, suggesting that ArnR senses nitrate derivatives generated during nitrate respiration. Specifically, the hmp gene is upregulated in the presence of nitrite or nitric oxide (NO) in an ArnR-dependent manner, although the response of narK appears to be greatly affected by ArnR-independent regulation. In vitro binding of ArnR to the narK and hmp promoter regions is more strongly inhibited by NO than by nitrite. We previously showed that UV-visible spectrum of ArnR is typical of a Fe-S cluster-containing protein. Site-directed mutagenesis of each of three cysteine residues, which are possibly involved in coordination of the cofactor in the ArnR protein, results in loss of the binding of this protein to its target promoters in vitro, and eliminates the repression of the target genes in vivo under aerobic conditions. These observations suggest that the cofactor coordinated by these three cysteine residues in the ArnR protein plays a critical role in the NO-responsive expression of the narKGHJI operon and hmp gene.
    Journal of bacteriology 10/2013; · 3.94 Impact Factor
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    ABSTRACT: Microbial production of isobutanol is made difficult by the chemical's high cell toxicity. Corynebacterium glutamicum, inherently one of the more isobutanol-tolerant industrial microorganisms, exhibits unprecedented productivity under oxygen deprivation, potentially allowing for high productivity of such toxic chemicals as isobutanol. Here, we show that development of C. glutamicum strains proficient in isobutanol production depends not only on modulating the activity of 2-keto acid decarboxylase (KDC) and isobutanol dehydrogenase (IBDH) and suppressing by-product formation, but also on optimizing the production process to eschew product inhibition. Isobutanol production under oxygen deprivation reached 343 mM (3.2% v/v) in strain IBU5 expressing kivd (encoding KDC) under the control of ldhA promoter and adhP (encoding IBDH from Escherichia coli MG1655) under the control of gapA promoter. This productivity is double the previously reported best productivity of 1.6% (v/v) and exceeds the 2.5% (v/v) limit beyond which cell growth becomes too severely suppressed. Irrespective, a cumulative 56.5% improvement on yield was possible with the combined effects of disruption of the ppc gene, encoding phosphoenolpyruvate carboxylase (PEPC), use of a NAD(+) -specific mutant acetohydroxyacid isomeroreductase (AHAIR), and overexpression of select glycolytic genes. Using oleyl alcohol to continuously extract the isobutanol from reaction mixture and tripling the cell concentration in the reaction mixture to 60 g dry cell/L stretched the yield to 78.1% and volumetric productivity to 981 mM (9.1% v/v). Biotechnol. Bioeng. 2013;9999: 1-11. © 2013 Wiley Periodicals, Inc.
    Biotechnology and Bioengineering 06/2013; · 3.65 Impact Factor
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    ABSTRACT: We previously demonstrated the simplicity of oxygen-deprived Corynebacterium glutamicum to produce D-lactate, a primary building block of next-generation biodegradable plastics, at very high optical purity by introducing heterologous D-ldhA gene from Lactobacillus delbrueckii. Here, we independently evaluated the effects of overexpressing each of genes encoding the ten glycolytic enzymes on D-lactate production in C. glutamicum. We consequently show that while the reactions catalyzed by glucokinase (GLK), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), phosphofructokinase (PFK), triosephosphate isomerase (TPI), and bisphosphate aldolase had positive effects on D-lactate productivity by increasing 98, 39, 15, 13, and 10 %, respectively, in 10 h reactions in minimal salts medium, the reaction catalyzed by pyruvate kinase had large negative effect by decreasing 70 %. The other glycolytic enzymes did not affect D-lactate productivity when each of encoding genes was overexpressed. It is noteworthy that all reactions associated with positive effects are located upstream of glycerate-1,3-bisphosphate in the glycolytic pathway. The D-lactate yield also increased by especially overexpressing TPI encoding gene up to 94.5 %. Interestingly, overexpression of PFK encoding gene reduced the yield of succinate, one of the main by-products of D-lactate production, by 52 %, whereas overexpression of GAPDH encoding gene increased succinate yield by 26 %. Overexpression of GLK encoding gene markedly increased the yield of dihydroxyacetone and glycerol by 10- and 5.8-fold in exchange with decreasing the D-lactate yield. The effect of overexpressing glycolytic genes was also evaluated in 80 h long-term reactions. The variety of effects of overexpressing each of genes encoding the ten glycolytic enzymes on D-lactate production is discussed.
    Applied Microbiology and Biotechnology 05/2013; · 3.69 Impact Factor
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    ABSTRACT: Expression plasmids that facilitate production of bio-based products are susceptible to toxic effects that frequently affect plasmid structural stability in recombinant microbial cells. In order to enhance plasmid stability in recombinant Corynebacterium glutamicum, an expression plasmid containing genes of the Clostridium acetobutylicum butyryl-CoA synthesis operon with high structural instability within wild-type C. glutamicum was employed. From a total of 133 mutants exhibiting disruptions in 265 suspect genes, only cgR_0322-deficient mutant was able to maintain the expression plasmid intact. The mutant exhibited normal growth under standard laboratory conditions but its transformation efficiency was about one order of magnitude lower than that of wild-type strain. The cgR_0322 gene encodes an endonuclease that is active against single- as well as double-stranded DNA substrates in the presence of Mg(2+). The cgR_0322-deficient strain should therefore facilitate the development of more robust C. glutamicum strains to be used as microbial production hosts.
    Applied Microbiology and Biotechnology 05/2013; · 3.69 Impact Factor
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    ABSTRACT: AIMS: To characterize the par system of C. glutamicum pCGR2 and to manipulate the par components to effectively manipulate plasmid copy number. METHODS AND RESULTS: ParB binds sequence-specifically to centromere-binding sites around the parAB operon and serves as an autorepressor. A small ORF (orf4, later named parC) downstream of parAB encodes a protein with 23.7% sequence identity with ParB. ParB is also implicated in the repression of parC transcription. Nonetheless, this ParC protein does not bind to centromere-binding sites and is not essential for plasmid stability. Introduction of a frameshift mutation within ParC implicated the protein in regulation of both parAB and parC. EMSA confirmed a previously unreported ParC-ParB-parS partition complex. ParC also interacts directly with ParB without the mediation of the centromere sites. Deletion of the par components resulted in different plasmid copy numbers. CONCLUSIONS: A previously unreported ParC-ParB-parS partition complex is formed in pCGR2, where interaction of ParC with ParB-parS may affect the level of repression by ParB. Modifying the par components and antisense RNA enables manipulation of plasmid copy number to varying degrees. This article is protected by copyright. All rights reserved.
    Journal of Applied Microbiology 05/2013; · 2.20 Impact Factor
  • Haruhiko Teramoto, Masayuki Inui, Hideaki Yukawa
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    ABSTRACT: OxyR, a LysR-type transcriptional regulator, has been established as a redox-responsive activator of antioxidant genes in bacteria. This study shows that OxyR acts as a transcriptional repressor of katA, dps, ftn, and cydA in Corynebacterium glutamicum R. katA encodes H2 O2 -detoxifing enzyme catalase, dps and ftn are implicated in iron homeostasis, and cydA encodes a subunit of cytochrome bd oxidase. Quantitative RT-PCR analyses revealed that expression of katA and dps, but not of ftn and cydA, was induced by H2 O2 . Disruption of the oxyR gene encoding OxyR resulted in a marked increase in katA and dps mRNAs to a level higher than that induced by H2 O2 , and the oxyR-deficient mutant showed a H2 O2 -resistant phenotype. This is in contrast to the conventional OxyR-dependent regulatory model. ftn and cydA were also upregulated by oxyR disruption but to a smaller extent. Electrophoretic mobility shift assays revealed that the OxyR protein specifically binds to all four upstream regions of the respective genes under reducing conditions. We observed that the oxidized form of OxyR similarly bound to not only the target promoter regions but also non-specific DNA fragments. Based on these findings, we propose that the transcriptional repression by OxyR is alleviated under oxidative stress conditions in a titration mechanism due to the decreased specificity of its DNA-binding activity. DNase I footprinting analyses revealed that the OxyR-binding site in the four target promoters is approximately 50 bp in length and has multiple T-N11 -A motifs, a feature of LysR-type transcriptional regulators, but no significant overall sequence conservation. This article is protected by copyright. All rights reserved.
    FEBS Journal 04/2013; · 4.25 Impact Factor
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    ABSTRACT: The central carbon metabolism genes in Corynebacterium glutamicum are under the control of a transcriptional regulatory network composed of several global regulators. It is known that the promoter region of ramA, encoding one of these regulators, interacts with its gene product RamA as well as with the two other regulators, GlxR and SugR, in vitro and/or in vivo. Although RamA has been confirmed to repress its own expression, the roles of GlxR and SugR in ramA expression have remained unclear. In this study, we examined the effects of GlxR binding site inactivation on expression of the ramA promoter-lacZ fusion in the genetic background of single and double deletion mutants of sugR and ramA. In the wild type background, the ramA promoter activity was reduced to undetectable levels by introducing mutations in the GlxR binding site, but increased by sugR deletion, indicating that GlxR and SugR function as transcriptional activator and repressor, respectively. The marked repression of ramA promoter activity by the GlxR binding site mutations was largely compensated for by deletions of sugR and/or ramA. Furthermore, ramA promoter activity in the ramA-sugR double mutant was comparable to that in the ramA mutant, but was significantly higher than that in the sugR mutant. Taken together, it is likely that the expression level of ramA is dynamically balanced by GlxR-dependent activation and repression by RamA along with SugR in response to perturbation of extracellular and/or intracellular conditions. These findings add multiple regulatory loops to the transcriptional regulatory network model in C. glutamicum.
    Journal of bacteriology 02/2013; · 3.94 Impact Factor
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    ABSTRACT: The function of three Corynebacterium glutamicum shikimate dehydrogenase homologues, designated as qsuD (cgR_0495), cgR_1216, and aroE (cgR_1677), was investigated. A disruptant of aroE required shikimate for growth, whereas a qsuD-deficient strain did not grow in medium supplemented with either quinate or shikimate as sole carbon sources. There was no discernible difference in growth rate between wild-type and a cgR_1216-deficient strain. Enzymatic assays showed that AroE both reduced 3-dehydroshikimate, using NADPH as cofactor, and oxidized shikimate, the reverse reaction, using NADP(+) as cofactor. The reduction reaction was ten times faster than the oxidation. QsuD reduced 3-dehydroquinate using NADH and oxidized quinate using NAD(+) as cofactor. Different from the other two homologues, the product of cgR_1216 displayed considerably lower enzyme activity for both the reduction and the oxidation. The catalytic reaction of QsuD and AroE was highly susceptible to pH. Furthermore, reduction of 3-dehydroshikimate by AroE was inhibited by high concentrations of shikimate, but neither quinate nor aromatic amino acids had any effect on the reaction. Expression of qsuD mRNA was strongly enhanced in the presence of shikimate, whereas that of cgR_1216 and aroE decreased. We conclude that while AroE is the main catalyst for shikimate production in the shikimate pathway, QsuD is essential for quinate/shikimate utilization.
    Applied Microbiology and Biotechnology 01/2013; · 3.69 Impact Factor
  • Alain A. Vertes, Masayuki Inui, Hideaki Yukawa
    01/2013: pages 1-49; , ISBN: 978-3-642-29856-1
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    ABSTRACT: We previously demonstrated efficient l-valine production by metabolically engineered Corynebacterium glutamicum under oxygen deprivation. To achieve the high productivity, a NADH/NADPH cofactor imbalance during the synthesis of l-valine was overcome by engineering NAD-preferring mutant acetohydroxyacid isomeroreductase (AHAIR) and using NAD-specific leucine dehydrogenase from Lysinibacillus sphaericus. Lactate as a by-product was largely eliminated by disrupting the lactate dehydrogenase gene ldhA. Nonetheless a few other by-products, particularly succinate, were still produced and acted to suppress the l-valine yield. Eliminating these by-products therefore was deemed key to improving the l-valine yield. By additionally disrupting the phosphoenolpyruvate carboxylase gene ppc, succinate production was effectively suppressed, but both glucose consumption and l-valine production dropped considerably due to the severely elevated intracellular NADH/NAD(+) ratio. In contrast, this perturbed intracellular redox state was more than compensated for by deletion of three genes associated with NADH-producing acetate synthesis and overexpression of five glycolytic genes including gapA encoding NADH-inhibited glyceraldehyde-3-phosphate dehydrogenase. Substituting with feedback-resistant mutant acetohydroxyacid synthase and NAD-preferring mutant AHAIR in the chromosome resulted in higher l-valine yield and productivity. Deleting the alanine transaminase gene avtA suppressed alanine production. The resultant strain produced 1,280 mM of l-valine at a yield of 88% mol mol of glucose(-1) after 24 h under oxygen deprivation, a vastly improved yield over our previous best.
    Applied and environmental microbiology 12/2012; · 3.69 Impact Factor
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    ABSTRACT: The non-essential Corynebacterium glutamicum sigma factor, sigB, modulates global gene expression during the transition from exponential growth to the stationary phase. Utilizing a signal peptide derived from C. glutamicum R CgR_0949, a sigB disruption mutant able to secrete 3- to 5-fold more green fluorescence protein (GFP) and α-amylase than the wild type strain was isolated. The signal peptide selectively enabled the mutant to produce greater amounts of both proteins, which were in turn secreted in culture medium in greater quantities than previously acknowledged. A peak GFP productivity of 2.8 g/l was attained, representing the highest GFP productivity reported in C. glutamicum to date. CgR_0949 signal sequence length (30 residues), type (Tat) or the target protein identity (GFP or α-amylase) had no measurable effect on the magnitude of the protein accumulation and consequent secretion. It therefore follows that actual experimentation remains the fastest way to identify suitable signal sequences in C. glutamicum. More secretion studies may reveal even greater secretion productivity by C. glutamicum and consequently present an attractive avenue to further enhance the utility of C. glutamicum as an industrial workhorse.
    Applied Microbiology and Biotechnology 11/2012; · 3.69 Impact Factor
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    ABSTRACT: Corynebacterium glutamicum produces 1,3-dihydroxyacetone (DHA) as metabolite of sugar catabolism but the responsible enzyme is yet to be identified. Using a transposon mutant library, the gene hdpA (cgR_2128) was shown to encode a haloacid dehalogenase superfamily member that catalyzes dephosphorylation of dihydroxyacetone phosphate to produce DHA. Inactivation of hdpA led to a drastic decrease in DHA production from each of glucose, fructose, and sucrose, indicating that HdpA is the main enzyme responsible for DHA production from sugars in C. glutamicum. Confirmation of DHA production via dihydroxyacetone phosphatase finally confirms a long-speculated route through which bacteria produce DHA.
    FEBS letters 10/2012; · 3.54 Impact Factor
  • Haruhiko Teramoto, Masayuki Inui, Hideaki Yukawa
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    ABSTRACT: Zur is a zinc-dependent transcriptional repressor of zinc uptake systems in bacteria. In this study, we examined the role of Corynebacterium glutamicum Zur in zinc-inducible expression of two genes, one encoding a cation diffusion facilitator (zrf) and the other a metal-translocating P-type ATPase (zra). Both genes were shown to be involved in zinc resistance. Disruption of the zur gene encoding Zur resulted in constitutive expression of zrf and zra mRNAs. Electrophoretic mobility shift assay revealed that the Zur protein binds to the zrf and zra promoters, in vivo activities of which were upregulated in response to excess zinc. Interestingly, the in vitro DNA binding activity of Zur was inhibited by zinc in contrast to its zinc-dependent binding to the promoter region of a zinc-repressible ABC transporter gene znuB2. A 21-bp motif found in the Zur binding site overlaps the putative -35 region of both the zrf and zra promoters. This new motif is a 10-1-10 direct repeat sequence distinct from the 10-1-10 inverted repeat sequence of a previously identified Zur box for zinc-dependent binding. Nevertheless, their 10-bp elements share some sequence similarities. Overexpression of zur in the zur deletion mutant background, as well as deletion of zur in the zrf and zra double deletion mutant background, resulted in decreased resistance to zinc. These results suggest that the direct negative control of both zinc uptake and export systems by Zur is central to C. glutamicum zinc homeostasis and is effected in distinct ways. © 2012 The Authors Journal compilation © 2012 FEBS.
    FEBS Journal 10/2012; · 4.25 Impact Factor
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    ABSTRACT: The transcriptional regulation of Corynebacterium glutamicum gnd encoding 6-phosphogluconate dehydrogenase was investigated. Two transcriptional regulators GntR1 and RamA were isolated by affinity purification using gnd promoter DNA. GntR1 was previously identified as a repressor of gluconate utilization genes including gnd. Involvement of RamA in gnd expression had not been investigated to date. The level of gnd mRNA was barely affected by single deletion of ramA. However, the gnd expression was downregulated in the ramA gntR1 double mutant compared to the gntR1 single mutant, suggesting that RamA activates gnd expression. Two RamA binding sites are found in the 5' -upstream of gnd. Mutation proximal to the transcriptional start site diminished the gluconate-dependent induction of the gnd-lacZ. DNase I footprinting assay revealed two GntR1 binding sites, one corresponding to a previously proposed site overlaps with the -10 region. The other site overlaps with the RamA binding site. GntR1 binding to this newly identified site inhibits the DNA binding of RamA. Therefore, it is likely that GntR1 represses gnd expression by preventing both RNA polymerase and RamA binding to the promoter. In addition, DNA binding activity of RamA was reduced by high concentrations of NAD(P)H but not by NAD(P), implying that RamA may sense the redox perturbation of the cell.
    Journal of bacteriology 09/2012; · 3.94 Impact Factor
  • Alain A Vertès, Masayuki Inui, Hideaki Yukawa
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    ABSTRACT: Corynebacterium glutamicum exhibits numerous ideal intrinsic attributes as a factory of primary and secondary metabolites. The versatile capabilities of this organism have long been implemented at the industrial scale to produce an array of amino acids at high yields and conversion rates, thereby enabling the development of an entire industry. The postgenomic era provides a new technological platform not only to further optimize the intrinsic attributes of C. glutamicum whole cells as biocatalysts, but also to dramatically expand the product portfolio that can be manufactured by this organism, from amino acids to commodity chemicals. This review addresses the methods and strain optimization strategies enabled by genomic information and associated techniques. Their implementation has provided important additional incremental improvements to the economics of industry-scale manufacturing in which C. glutamicum and its episomal elements are used as a performing host-vector system.
    Annual review of microbiology 07/2012; 66:521-50. · 12.80 Impact Factor
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    ABSTRACT: Plastidial phosphoglucomutase (PGM) plays an important role in starch synthesis and degradation. Nonetheless, the impact of enhanced plastidial PGM activity on metabolism in photosynthetic tissue is yet to be elucidated. In this study, we generated transplastomic tobacco plants overproducing Arabidopsis thaliana plastidial PGM (AtptPGM) in chloroplasts and analyzed the consequent metabolic and physiological parameters in the transplastomic plants. AtptPGM accumulated in the chloroplasts to up to 16% of total soluble protein in the leaves. PGM activity in leaves increased 100-fold relative to that of wild-type plants. The transplastomic plants were phenotypically indistinguishable in their growth rates, photosynthetic activities, and starch synthesis from wild-type plants, but hexose partitioning in the light period was dramatically different. Furthermore, alteration of extracellular invertase activity was observed in the lower leaves of the transplastomic plants. These observations suggest that high-level expression of plastidial PGM alters hexose partitioning in light periods via modification of extracellular invertase activity.
    Bioscience Biotechnology and Biochemistry 07/2012; 76(7):1315-21. · 1.27 Impact Factor

Publication Stats

3k Citations
582.49 Total Impact Points

Institutions

  • 1995–2014
    • Research Institute of Innovative Technology for the Earth
      Kioto, Kyōto, Japan
    • Battelle Memorial Institute
      Columbus, Ohio, United States
  • 2005–2011
    • Nara Institute of Science and Technology
      • Graduate School of Biological Sciences
      Ikuma, Nara, Japan
  • 2010
    • University of Illinois, Urbana-Champaign
      • Center for Advanced BioEnergy Research
      Urbana, IL, United States
  • 2003–2007
    • University of California, Davis
      • Department of Molecular and Cellular Biology
      Davis, CA, United States
  • 2006
    • Kyushu University
      • Department of Bioscience and Biotechnology
      Fukuoka-shi, Fukuoka-ken, Japan
  • 2004
    • The University of Calgary
      • Department of Biological Sciences
      Calgary, Alberta, Canada
  • 2002
    • Mitsubishi Corp.
      Ibaragi, Ōsaka, Japan
  • 2000
    • Hungarian Academy of Sciences
      Budapeŝto, Budapest, Hungary
  • 1999
    • Mitsubishi Chemical Group Science and Technology Research Center, Inc.
      Yokohama, Kanagawa, Japan
  • 1996–1997
    • Kyoto University
      • Division of Food Science and Biotechnology
      Kyoto, Kyoto-fu, Japan