• Proceedings of the Zoological Society Korea Conference
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• 1995.10b
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• pp.82-82
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• 1995

Regulation of enzyme synthesis by transcriptional and translational control systems provides rather stable adaptation to change of amino acid level in the growth medium, while manipulation of enzyme activity through endproduct feedback inhibition represents rather short-term and reversible ways of adjusting metabolic fluctuation of amino acid level. Various control mechanisms interplay to regulate genes encoding enzymes for amino acid biosynthesis in the yeast, Sacchromyces cerevisiae. When amino acids are in short supply, genes under a cross-pathway regulatory mechanism Or general amino acid control (general control) increase their action, in which Gcn4p is the major positive regulator of gene expression. When cells are cultured in minimal medium, basal level expression is also regulated by supplementary control elements, where inorganic phosphate level is additionally involved. Most of amino acid biosynthetic genes are also regulated by the level of endproduct of the pathway. This pathway-specific regulatory mechanism is called specific amino acid control (specific controD, under which gene expression is reduced when endproduct is present in the medium. Derepression of a gene through general control can be usually overridden by repression through specific control, where the endproduct level of that particular pathway is high and not limiting. In this presentation, regulatory factors for basal level expression and general control of yeast amino acid biosynthesis will be discussed, m addition to pathway-specific repression patterns and interaction between CrOSS- and specific-control mechanisms. Preliminary results are also presented from the investigation of the cloned genes in the threonine biosynthetic pathway of the yeast. yeast.

• YAKHAK HOEJI
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• v.43 no.1
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• pp.61-67
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• 1999

Geranyllinalool, a polyisoprenoid compound, was found to block the early biosynthetic pathway of sphingolipids in LLC-PKl cells. Sphinganine, an intermediate in sphingolipid biosynthetic pathway, was abruptly accumulated in LLC-PKl cells at $2{\;}{\mu}M$ of fumonisin B1(FB1), a specific inhibitor of sphinganine N-acyltransferase, for 24 hr. Geranyllinalool lowered the $B_1(FB_1)$, a specific inhibitor of sphinganine N-acyltransferase, for 24 hr. Geranyllinalool lowered th FB1 and $50{\;}\mu$M geranyllinalool. l-Cy-closerine, an inhibitor of serine-palmitoyl transferase, was used as a positive control to evaluate the inhibitory effect of geranyllinalool. These results suggest that geranyllinalool may inhibit the serine-palmitoyl transferase, the first enzyme in de novo sphingolipid biosynthesis, resulting in the altered regulation of sphingolipid metabolism.

• The Microorganisms and Industry
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• v.12 no.2
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• pp.30-35
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• 1986

Almost all of the aerobic organisms contain citric acid cycle (or, tricarboxylic acid cycle). This cycle is involved both in energy metabolism and biosynthetic reactions; generation of NADH which derives the synthesis of chemical energy, ATP, and provision of intermediates needed for the biosynthesis. Because of its importance in the cellular metabolism, the regulation of the TCA cycle and its component enzymes has been extensively studied by many biologists (7,28). Citrate synthase is resposible for the initial step of the cycle and has been recognized as the rate limiting step (14,121,26). Understanding of the mechanism of the expression of citrate synthase should be a key step for the elucidation of the regulation of the TCA cycle in the cell metabolism.

• Korean Journal of Microbiology
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• v.29 no.3
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• pp.160-166
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• 1991

The regulatory mechanism of tubercidin biosynthesis in Streptomyces tubercidicus was studied. In a wild type strain, addition of adenine and histidine into the medium decreased the tubercidin production by 60-65% and 40%, respectively. The effects of adenine and histidine were alleviated by the addition of inosine monophosphate and 5-aminoimidazole-4-carboxamide ribotide. The production of tubercidin in S. tubercidicus K115 strain ($ade^{-}$ ) was nearly shut off by histidine. In contrast with K115 strain, adenine inhibited the tubercidin biosynthesis in S. tubercidicus K412 strain ($his^{-}$. In S. tubercidicus F667 strain ($ade^{-}$ , $his^{-}$ ), tubercidin production was increased by adenine and histidine. From the effects of adenine and histidine on tubercidin biosynthesis in S. tubercidicus wild type and mutant strains, it became known that feedback control by adenine and histidine of biosynthetic pathwat for purine ribonucleotide and histidine are involved in the regulation of tubercidin biosynthesis.

• Journal of Life Science
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• v.11 no.2
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• pp.120-125
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• 2001

The pyrR gene of the pyrimidine biosynthesis (pyr) operon of the thermophile Bacillus caldolyticus, encoding a uracil phosphoribosyltransferase (UPRTase), turned to rely as a pyr operon regulator. It has been proposed that PyrR mediates transcriptional termination-antitermination at three intercistronic regions of the par operon (S.-Y Ghim and J. Neuhard, J. Bacteriol.,176, 3698-3707, 1994). In this research, a plasmid carrying the pyrR region of B. caldolyticus could restore a pyrimidine regulation in a pyrR mutant of B. subtilis. Expression of pyrR was found to increase 6-7 fold during pyrimidine starvation. Additionally, a highly conserved nucleotide sequence which may constitute the binding site for a PyrR protein (PyrR-binding loop) in transcript was staggested. Alternative antiterminator and terminator structures involving three conserved motifs in front of the pyrR, pyrP and pyrB genes, respectively, are proposed to account for the observed regulation pattern.

• Journal of Plant Biotechnology
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• v.45 no.2
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• pp.83-89
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• 2018

The interplay of plant hormones is one of the essential mechanisms for plant growth and development. A recent study reported that Brassinosteroids (BR) and ABSCISIC ACID (ABA) interact antagonistically in early seedling developments through the BR-mediated epigenetic repression of ABSCISIC ACID-INSENSITIVE 3 (ABI3). However, the other physiological roles of the BR-mediated regulation of ABI3 and ABA responses beyond early seedling developments remain largely unknown. Here, we showed that the activation of BR signaling by high temperatures promotes flowering time through the suppression of ABI3 expressions. Elevated ambient temperature induced early flowering in wild type Col-0 plants, but not in BR-defective bri1-116 mutant plants. Conversely, a hyper BR biosynthetic dwf4-D mutant displayed more sensitive thermomorphic long shoot elongation and early flowering. Both expression patterns and physiological responses supported the biological roles of ABI3 in the regulation of floral transition and reproduction under high temperature conditions. Finally, we confirmed that the lowered expressions of the transcript and protein levels of ABI3 brought on by elevated temperature were correlated with warmth-induced early flowering phenotypes. In conclusion, our data suggest that the BR- and warmth-mediated regulation of ABI3 are important in thermomorphic reproductive phase transitions in plants.

• Proceedings of the Botanical Society of Korea Conference
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• 1987.07a
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• pp.323-347
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• 1987

The R locus of maize in one of several genes that regulate the anthocyanin pigments throughout the body of the plant and seed. The R gene product may regulate pigment deposition by controlling the expression of the flavonoid biosynthetic gene pathway in a tissue-specific manner. To understand the basis for tissue specific regulation and allelic variation at R, the molecular study has been done by cloning a portion of the R complex by transposon tagging with Ac. R specific probe were cloned from the R-nj mutant induced by Ac insertion mutagenesis. From southern analysis of R-r complex using the R-nj probe, the structure of R-r was proposed that R-r containes the three elements, (P)(Q)(S). These elements may organize as the inversion triplication model which (S) sequence was inverted in relation to (P) and (Q). The R-sc derivated from R-mb or R-nj was cloned with R-nj probe, and molecular genetical data showed that R-sc containes tissue specific and tissue nonspecific area, and the sequencing of R-sc are progressed now.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1841-1848
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• 2006

Insights into gene expression have the potential for improvement of antibiotic yield and the development of robust production hosts for use in recombinant biomolecule production. $Cubicin^{TM}$ (daptomycin for injection) is a recently approved antibiotic active against many Gram(+) pathogens, including those resistant to methicillin, vancomycin, and fluoroquinolones. Daptomycin is produced as a secondary metabolite by Streptomyces roseosporus. A 128 kb region of DNA including the daptomycin biosynthetic gene cluster (dpt) has been cloned. and sequenced. Using a selected array of nucleic acid probes representing this region, we compared the expression levels of the dpt genes between S. roseosporus wild-type (WT) and derived S. roseosporus high-producer of daptomycin (HP). We observed that the majority of the biosynthetic genes were upregulated in HP compared with WT; a total of 12 genes, including those encoding daptomycin synthetase, showed consistently and significantly higher expression levels, at least 5-fold, in HP compared with WT. In contrast, some genes, flanking the dpt cluster, were expressed at higher levels in the WT strain. The expression of housekeeping genes such as S. roseosporus rpsL, rpsG, and 16S (positive controls) and presumptive intergenic regions in the dpt cluster (negative control) were identical in the two strains. In addition, we compared transcription during the early, mid-log, and early-stationary phases of growth in the HP strain. The same set of genes was upregulated and downregulated under all conditions examined; housekeeping genes showed no relative change in expression level over the periods of growth tested. Analyses of this type would be of value in studies of strain improvement and also for the identification of gene regulation processes that are important for secondary metabolite production.

• 한국균학회소식:학술대회논문집
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• 2016.05a
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• pp.27-27
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• 2016

The ascomycete fungus Fusarium graminearum is the most common pathogen of Fusarium head blight (FHB), a devastating disease for major cereal crops worldwide. FHB causes significant crop losses by reducing grain yield and quality as well as contaminating cereals with trichothecenes and zearalenone (ZEA) that pose a serious threat to animal health and food safety. ZEA is a causative agent of hyperestrogenic syndrome in mammals and can result in reproductive disorders in farm animals. In F. graminearum, the ZEA biosynthetic cluster is composed of four genes, PKS4, PKS13, ZEB1, and ZEB2, which encode a reducing polyketide synthase, a nonreducing polyketide synthase, an isoamyl alcohol oxidase, and a transcription factor, respectively. Although it is known that ZEB2 primarily acts as a regulator of ZEA biosynthetic cluster genes, the mechanism underlying this regulation remains undetermined. In this study, two isoforms (ZEB2L and ZEB2S) from the ZEB2 gene in F. graminearum were characterized. It was revealed that ZEB2L contains a basic leucine zipper (bZIP) DNA-binding domain at the N-terminus, whereas ZEB2S is an N-terminally truncated form of ZEB2L that lacks the bZIP domain. Interestingly, ZEA triggered the induction of both ZEB2L and ZEB2S transcription. In ZEA producing condition, the expression of ZEB2S transcripts via alternative promoter usage was directly or indirectly initiated by ZEA. Physical interaction between ZEB2L and ZEB2L as well as between ZEB2L and ZEB2S was observed in the nucleus. The ZEB2S-ZEB2S interaction was detected in both the cytosol and the nucleus. ZEB2L-ZEB2L oligomers activated ZEA biosynthetic cluster genes, including ZEB2L. ZEB2S inhibited ZEB2L transcription by forming ZEB2L-ZEB2S heterodimers, which reduced the DNA-binding activity of ZEB2L. This study provides insight into the autoregulation of ZEB2 expression by alternative promoter usage and a feedback loop during ZEA production.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.828-836
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• 2008

The biocontrol rhizobacterium Pseudomonas sp. M18 can produce two kinds of antibiotics, namely pyoluteorin (Plt) and phenazine-1-carboxylic acid (PCA), and is antagonistic against a number of soilborne phytopathogens. In this study, a luxR-type quorum-sensing regulatory gene, vqsR, was identified and characterized immediately downstream of the Plt gene cluster in strain MI8. A vqsR-inactivated mutant led to a significant decrease in the production of Plt and its biosynthetic gene expression. However, this was restored when introducing the vqsR gene by cloning into the plasmid pME6032 in trans. The vqsR mutation did not exert any obvious influence on the production of PCA and its biosynthetic gene expression and the production of N-acylhomoserine lactones (C4 and C8-HSLs) and their biosynthetic gene rhlI expression. Accordingly, these results introduce VqsR as a regulator of Plt production in Pseudomonas spp., and suggest that the regulatory mechanism of vqsR in strain M18 is distinct from that in P. aeruginosa. In addition, it was demonstrated that vqsR mutation did not have any obvious impact on the expression of Plt-specific ABC transporters and other secondary metabolic global regulators, including GacA, RpoS, and RsmA.