• Journal of Plant Biology
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• v.39 no.2
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• pp.85-92
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• 1996

Small GTP-binding proteins are divided into three major group: Ras, Rho and Ypt/Rab. They have the conserved regions designed G1 to G5 that are critical in GDP/GTP exchange, GTP-induced conformational change and GTP hydrolysis. We isolated and characterized genomic DNA or cDNAfragments encoding G1 to G3 domains of small GTP-binding protein Rab and Rho from several plant species using two different PCR-based cloning strategies. Seven rab DNA fragments were isolated from 4 different plants, mung-bean, tobacco, rice and pepper using two degenerate primers corresponding to the GTP-binding domain G1 and G3 in small GTP-binding proteins. The amino acid sequences among these rab DNA fragments and other known small GTP-binding proteins shows that they belong to the Ypt/Rab family. Six rho DNA fragments were isolated from 5 different plants, mung-bean, rice, Arabidopsis, Allium and Gonyaulax using the nested PCR method that involves four degenerate primers corresponding to the GTP-binding domain G1, G3 and G4. The rho DNA fragments cloned show more than 90% homology to each other. Sequence comparison between plant and other known Rho family genes suggests that they are closely related (67 to 82% amino acid identity). Sequence analysis and southern blot analysis of rab and rho in mung-bean suggest than thses genes are encoded by multigene family in mung-bean.

• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.55-61
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• 2016

Sepiapterin, a precursor for tetrahydrobiopterin, is produced in higher mammals using guanosine triphosphate (GTP) as a biosynthetic intermediate. Four genes involved in GTP biosynthesis, namely those of guanosine monophosphate kinase (gmk), nucleoside diphosphate kinase (ndk), guanosine phosphate synthetase (guaA), and inosine-5'-monophosphate dehydrogenase (guaB), were expressed in sepiapterin-producing recombinant Escherichia coli BL21(DE3) to increase intracellular GTP concentration and to improve sepiapterin production concomitantly. Coexpression of gmk, ndk, guaA, and guaB, doubled the intracellular GTP concentration and increased the maximum sepiapterin concentration up to $126.1{\pm}19.3mg/l$ (an increase of 43% compared with control cells) in batch-cultivated recombinant E. coli.

• Journal of Plant Biotechnology
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• v.40 no.1
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• pp.9-17
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• 2013

Ran is a small GTP-binding protein that binds and subsequently hydrolyzes GTP. The functions of Ran in nuclear transport and mitotic progression are well conserved in plants and animals. In animal cells, stress treatments cause Ran relocalization and slowing of nuclear transport, but the role of Ran proteins in plant cells exposed to stress is still unclear. We have therefore compared Ran genes from three EST libraries construed from different cell types of sweetpotato and the distribution pattern of Ran ESTs differed according to cell type. We further characterized two IbRan genes. IbRan1 is a specific EST to the suspension cells and leaf libraries, and IbRan2 is specific EST to the root library. IbRan1 showed 94.6 % identity with IbRan2 at the amino acid level, but the C-terminal region of IbRan1 differed from that of IbRan2. These two genes showed tissue-specific differential regulation in wounded tissues. Chilling stress induced a similar expression pattern in both IbRan genes in the leaves and petioles, but they were differently regulated in the roots. Hydrogen peroxide treatment highly stimulated IbRan2 mRNA expression in the leaves and petioles, but had no significant effect on IbRan1 gene expression. These results showed that the transcription of these two IbRan genes responds differentially to abiotic stresses and that they are subjected to tissue-specific regulation. Plant Ran-type small G-proteins are a multigenic family, and the characterization of each Ran genes under various environmental stresses will contribute toward our understanding of the distinctive function of each plant Ran isoform.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.2
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• pp.75-88
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• 2001

In this paper, the microbial production of riboflavin is reviewed and includes descriptions of riboflavin overproducers, and the biosynthesis and details of the key-enzyme genes related to riboflavin. There kinds of riboflavin overproducers are known; Bacillus subtilis and Candida famate utilize glucose as a carbon source, but the fungus Ashbya gossypii requires plant oil as its sole carbon source. The starting material in ribofalvin biosynthesis is guanosine triphospate (GTP), which is converted to riboflavin through six enzymatic reactions. Though Bacillus subtilis, Candida famate, and Ashbya gossypii operate via different pathways until GTP, they follow the same pathway from GTP to riboflavin. From the metabolic viewpoint, with respect to improved riboflavin production, the supplementation of GTP, aprocess-limiting precursor must be considered. The GTP fluxes originate from three sources, serine, threonine and glyoxylate cycles. The development of pathways to strengthen GTP supplementation using biotechnological techniques remains an issue fro future research.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.81.2-82
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• 2003

Plants have evolved along with pathogens, and they have developed sophisticated defense systems against specific microorganisms to survive. G-protons are considered one of the upstream signaling components working as a key for the defense signal transduction pathway. For activation and inactivation of G-protein, GTP-biding proteins are involved. GTP -binding proteins are found in all organisms. Small GTP-binding proteins, having masses of 21 to 30kD, belong to a superfamily, often named the Ras supefamily because the founding members are encoded by human Ras genes initially discovered as cellular homologs of the viral ras oncogene. Members of this supefamily share several common structural features, including several guanine nucleotide binding domains and an effector binding domain. However, exhibiting a remarkable diversity in both structure and function. They are important molecular switches that cycle between the GDP-bound inactive form into the GTP-bound active form through GDP/GTP replacement. In addition, most GTP-binding proteins cycle between membrane-bound and cytosolic forms. such as the RAC family are cytosolic signal transduction proteins that often are involved in processing of extracellular stimuli. Plant RAC proteins are implicated in regulation of plant cell architecture secondary wall formation, meristem signaling, and defense against pathogens. But their molecular mechanisms and functions are not well known. We isolated a RacB homolog from rice to study its role of defense against pathogens. We introduced the constitutively active and the dominant negative forms of the GTP-hinging protein OsRacB into the wild type rice. The dominant negative foms are using two forms (full-sequence and specific RNA interference with RacB). Employing southern, and protein analysis, we examine to different things between the wild type and the transformed plant. And analyzing biolistic bombardment of onion epidermal cell with GFP-RacB fusion protein revealed association with the nucle.

• Journal of Life Science
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• v.23 no.1
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• pp.8-14
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• 2013

Genes expressed during conidial germination of the pepper anthracnose fungus Colletotrichum acutatum were identified by sequencing the 5' end of unidirectional cDNA clones prepared from the conidial germination stage. A total of 983 expressed sequence tags (ESTs) corresponding to 464 genes, 197 contigs and 267 singletons, were generated. The deduced protein sequences from half of the 464 genes showed significant matches (e value less than 10-5) to proteins in public databases. The genes with known homologs were assigned to known functional categories. The most abundantly expressed genes belonged to those encoding the elongation factor, histone protein, ATP synthease, 14-3-3 protein, and clock controlled protein. A number of genes encoding proteins such as the GTP-binding protein, MAP kinase, transaldolase, and ABC transporter were detected. These genes are thought to be involved in the development of fungal cells. A putative pathogenicity function could be assigned for the genes of ATP citrate lyase, CAP20 and manganese-superoxide dismutase.

• Korean Journal of Microbiology
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• v.38 no.3
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• pp.173-179
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• 2002

The functions of riboflavin synthesis genes ( ribI,II,III and IV) found immediately downstream of luxG in the lux operon from Photobacterium species were identified using the biochemical and genetical analysis. The ribI-III gene codes for protein corresponding to that coded by the second (riboflavin synthase), third (3,4-dihydroxy 2-butanone 4-phosphate synthase/GTP cyclohydrolase II) and fourth (lumazine synthase) gene, respectively, of Bacillus subtilis rib operon with the respective gene procuct sharing 41-50% amino acid sequence identity. Unexpectedly, the sequence of the ribIV product of Photobacterium phosphoreum does not correspond in sequence to the protein encoded by the fifth rib gene of Bacillus subtilis. Instead the gene (ribIV) codes for a polypeptide similar in sequence to GTP cyclohydrolase II of Escherichia coli and the carboxy terminal domain of the third rib gene from Bacillus subtilis. Complementation of Escherichia coli riboflavin auxotrophs showed that the function of the gene products of ribII and ribIV are DHBP synthase and GTP cyclohydrolase II, respectively. In addition the experiment, showing that increase in thermal stability of riboflavin synthase coded by ribIon coexpression with ribIII, provided indirect evidence that the latter gene codes for lumazine synthase.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1484-1490
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• 2010

In the Streptomyces hygroscopicus JCM4427 geldanamycin biosynthetic gene cluster, five putative regulatory genes were identified by protein homology searching. Among those genes, gel14, gel17, and gel19 are located downstream of polyketide synthase genes. Gel14 and Gel17 are members of the LAL family of transcriptional regulators, including an ATP/GTP-binding domain at the N-terminus and a DNA-binding helix-turn-helix domain at the C-terminus. Gel19 is a member of the TetR family of transcriptional regulators, which generally act to repress transcription. To verify the biological significance of the putative regulators in geldanamycin production, they were individually characterized by gene disruption, genetic complementation, and transcriptional analyses. All three genes were confirmed as positive regulators of geldanamycin production. Specifically, Gel17 and Gel19 are required for gel14 as well as gelA gene expression.

• Molecules and Cells
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• v.27 no.5
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• pp.583-589
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• 2009

GTP cyclohydrolase I (GTPCH) is a key enzyme in the de novo synthesis of tetrahydrobiopterin. Previously, the Drosophila melanogaster GTPCH gene has been shown to be expressed from two different promoters (P1 and P2). In our study, the 5'-flanking DNA regions required for P1 and P2 promoter activities were characterized using transient expression assay. The DNA regions between -98 and +31, and between -73 and +35 are required for efficient P1 and P2 promoter activities, respectively. The regions between -98 and -56 and between -73 and -41 may contain critical elements required for the expression of GTPCH in Drosophila. By aligning the nucleotide sequences in the P1 and P2 promoter regions of the Drosophila melanogaster and Drosophila virilrs GTPCH genes, several conserved elements including palindromic sequences in the regions critical for P1 and P2 promoter activities were identified. Western blot analysis of transgenic flies transformed using P1 or P2 promoter-lacZ fusion plasmids further revealed that P1 promoter expression is restricted to the late pupae and adult developmental stages but that the P2 promoter driven expression of GTPCH is constitutive throughout fly development. In addition, X-gal staining of the embryos and imaginal discs of transgenic flies suggests that the P2 promoter is active from stage 13 of embryo and is generally active in most regions of the imaginal discs at the larval stages.

• Korean Journal of Agricultural Science
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• v.34 no.2
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• pp.161-170
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• 2007

To characterize $\gamma$-glutamyltranspeptidase ($\gamma$-GTP or ggt; EC 2. 3. 2. 2.) gene of Bacillus subtilis BS 62, the $\gamma$-GTP gene of BS 62 was prepared from PCR products amplified with the chromosomal DNA. The $\gamma$-GTP gene of about 2.5 kb was sequenced, and its homology was compared with the other ggt genes which were reported previously. The base sequence of the gene appeared to have an open reading frame of 1,758 bp encoding a protein of 62,175 Da. The coding region was flanked by putative ribosome binding site - AGGAGG of 7th to 12th upstream - and the stem-loof sequence was followed by transcription terminator codon. Homology of the amino acid residues sequence consisting of 587 amino acid residues was found as 98% with Bacillus subtilis gene (BSU49358), 97.4% with that of Bacillus subtilis KX 102, 37% with Pseudomonas sp. A14 (S63255) and 38% with Streptomyces avermitils (AP005028).