• Applied Biological Chemistry
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• v.37 no.5
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• pp.361-369
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• 1994

To study the light-induced expression mechanism and protein transport into the chloroplast, a rice genomic clone (GrbcS) for the small subunit of ribulose 1,5-bisphosphate carboxylase (rbcS) was isolated and its nucleotide sequence was determined. Nucleotide sequence analysis of GrbcS revealed that the gene consists of two exons interrupted by an intron, encoding a protein of 175 amino acids including a transit peptide of 47 amino acids. These structural features of GrbcS are consistent with those of other rbcS genes from monocot species. Genomic Southern blot analysis suggested that the rbcS genes are present as a relatively small multigene family in the rice genome. Comparison of the nucleotide and deduced amino acid sequences to other rice rbcSs shows close sequence similaritiy. Conserved DNA sequences present in other light-responsive genes are also found in the 5’ upstream region of GrbcS such as G-box, 3AF1-binding site and GATA site. The possible function of these putative regulatory elements are discussed.

• BMB Reports
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• v.53 no.5
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• pp.260-265
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• 2020

Scorpion venom comprises a cocktail of toxins that have proven to be useful molecular tools for studying the pharmacological properties of membrane ion channels. HelaTx1, a short peptide neurotoxin isolated recently from the venom of the scorpion Heterometrus laoticus, is a 25 amino acid peptide with two disulfide bonds that shares low sequence homology with other scorpion toxins. HelaTx1 effectively decreases the amplitude of the K⁺ currents of voltage-gated Kv1.1 and Kv1.6 channels expressed in Xenopus oocytes, and was identified as the first toxin member of the κ-KTx5 subfamily, based on a sequence comparison and phylogenetic analysis. In the present study, we report the NMR solution structure of HelaTx1, and the major interaction points for its binding to voltage-gated Kv1.1 channels. The NMR results indicate that HelaTx1 adopts a helix-loop-helix fold linked by two disulfide bonds without any β-sheets, resembling the molecular folding of other cysteine-stabilized helix-loop-helix (Cs α/α) scorpion toxins such as κ-hefutoxin, HeTx, and OmTx, as well as conotoxin pl14a. A series of alanine-scanning analogs revealed a broad surface on the toxin molecule largely comprising positively-charged residues that is crucial for interaction with voltage-gated Kv1.1 channels. Interestingly, the functional dyad, a key molecular determinant for activity against voltage-gated potassium channels in other toxins, is not present in HelaTx1.

• Journal of Life Science
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• v.15 no.5 s.72
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• pp.734-738
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• 2005

A gene coding for xylanase from alkali-tolerant Bacillus alcalophilus AX2000 was cloned into Escherichia coli $DH5\alpha$ using pUC19. Among 2,000 transformants, one transformant showed clear zone on the detection agar plate containing oat-spells xylan. Its recombinant plasmid, named pXTY99, was found to carry 7.0 kb insert DNA fragment. When the nucleotide sequence of the cloned xylanase gene (xynT) was determined, xynT gene was found to consist of 1,020 base-pair open reading frame coding for a poly-peptide of 340 amino acids with a deduced molecular weight of 40 kDa. The coding sequence was preceded by a putative ribosome binding site, and the transcription initiation signals. The deduced amino acid sequence of xylanase is similar to those of the xylanases from Bacillus sp. Nl37 and B. stearothermophilus 21 with $61\%$ and $59\%$ identical residues, respectively.

• Molecules and Cells
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• v.27 no.6
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• pp.651-656
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• 2009

The formation of ${\beta}$-amyloid peptide ($A{\beta}$) is initiated from cleavage of amyloid precursor protein (APP) by a family of protease, ${\alpha}$-, ${\beta}$-, and ${\gamma}$-secretase. Sub W, a substrate peptide, consists of 10 amino acids, which are adjacent to the ${\beta}$-cleavage site of wild-type APP, and Sub M is Swedish mutant with double mutations on the left side of the ${\beta}$-cleavage site of APP. Sub W is a normal product of the metabolism of APP in the secretary pathway. Sub M is known to increase the efficiency of ${\beta}$-secretase activity, resulting in a more specific binding model compared to Sub W. Three-dimensional structures of Sub W and Sub M were studied by CD and NMR spectroscopy in water solution. On the basis of these structures, interaction models of ${\beta}$-secretase and substrate peptides were determined by molecular dynamics simulation. Four hydrogen bonds and one water-mediated interaction were formed in the docking models. In particular, the hydrogen bonding network of Sub M-BACE formed spread over the broad region of the active site of ${\beta}$-secretase (P5-P3'), and the side chain of P2- Asn formed a hydrogen bond specifically with the side chain of Arg235. These are more favorable to the cleavage of Sub M by ${\beta}$-secretase than Sub W. The two substrate peptides showed different tendency to bind to ${\beta}$-secretase and this information may useful for drug development to treat and prevent Alzheimer's disease.

• BMB Reports
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• v.30 no.5
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• pp.356-361
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• 1997

We cloned a cDNA (pPRC-1) which was comprised of 841 nucleotides from the cDNA library of a male ICR mouse submandibular gland ($SMG^+$). The nucleotide sequences of pPRC-1 were identical to those of exons 2 and 3 of the mGK-21 gene, a potentially functional glandular kallikrein identified in a Balb/c mouse, except for one nucleotide residue. Although this substitution changes Ile (ATT) in pPRC-1 to Val (GTT) in mGK-21, this difference has been explained by strain polymorphism. From the amino acid sequences predicted from its cDNA, we speculated that mGK-21 gene products/pGK21 consist of 261 amino acids including the $NH_2$-terminal signal peptide (residues 1~17), the short propeptide (residues 17~24), and the active peptide (residues 25~261). Although we did not demonstrate the enzyme activity of pGK21, it was assumed that pGK 21 was involved in the maturation of certain bioactive polypeptide(s) in mouse SMG for the following reasons : (a) mGK-21 gene was apparently expressed in a male ICR mouse SMG: (b) the proposed active site $His^{65}$, $Asp^{120}$, and $Ser^{213}$ residues were completely conserved in pGK21 just like other glandular kallikreins; (c) the cloned cDNA was translated to a predicted 27 kDa polypeptide chain in vitro: (d) the 27 kDa polypeptide chain produced by CHO cells was produced to a putative active form by trypsin.

• Korean Journal of Microbiology
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• v.48 no.2
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• pp.87-92
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• 2012

The purpose of this study was to examine the cellular response of Salmonella typhimurium exposed to tea polyphenols (TPP) extracted from Korean green tea (Camellia sinensis L.). TPP showed a dose-dependent bactericidal effect on S. typhimurium. Analysis of cell membrane fatty acids of S. typhimurium cultures treated with TPP identified unique changes in saturated and unsaturated fatty acids, while scanning electron microscopic analysis demonstrated the presence of perforations and irregular rod forms with wrinkled surfaces in cells treated with TPP. Two-dimensional polyacrylamide gel electrophoresis of soluble protein fractions from S. typhimurium cultures showed 16 protein spots increased by TPP. These up-regulated proteins including proteins involved in antioxidants and chaperons, transcript and binding proteins, energy and DNA metabolism were identified by peptide mass fingerprinting using MALDI-TOF. These results provide clues for understanding the mechanism of TPP induced stress and cytotoxicity on S. typhimurium.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.735-742
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• 2013

Peptide nucleic acids (PNAs) that bind to complementary nucleic acid sequences with extraordinarily high affinity and sequence specificity can be used as antisense oligonucleotides against microRNAs, namely antagomir PNAs. However, methods for efficient cellular delivery must be developed for effective use of PNAs as therapeutic agents. Here, we demonstrate that antagomir PNAs can be delivered to hepatic cells by complementary DNA oligonucleotide and cationic liposomes containing galactosylated ceramide and a novel cationic lipid, DMKE (O,O'-dimyristyl-N-lysyl glutamate), through glycoprotein-mediated endocytosis. An antagomir PNA was designed to target miR-122, which is required for translation of the hepatitis C virus (HCV) genome in hepatocytes, and was hybridized to a DNA oligonucleotide for complexation with cationic liposome. The PNA-DNA hybrid molecules were efficiently internalized into hepatic cells by complexing with the galactosylated cationic liposome in vitro. Galactosylation of liposome significantly enhanced both lipoplex cell binding and PNA delivery to the hepatic cells. After 4-h incubation with galactosylated lipoplexes, PNAs were efficiently delivered into hepatic cells and HCV genome translation was suppressed more than 70% through sequestration of miR-122 in cytoplasm. PNAs were readily released from the PNA-DNA hybrid in the low pH environment of the endosome. The present study indicates that transfection of PNA-DNA hybrid molecules using galactosylated cationic liposomes can be used as an efficient non-viral carrier for antagomir PNAs targeted to hepatocytes.

• BMB Reports
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• v.28 no.1
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• pp.72-78
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• 1995

Time-dependent inactivation of E. coli GTP cyclohydrolase I with a 2',3'-dialdehyde derivative of GTP (oGTP) was directed to the active site of the enzyme, and was dependent on the concentration of oGTP. The kinetics of inactivation were biphasic with a rapid reaction occurring immediately upon exposure of the enzyme to oGTP followed by a slow rate of inactivation. The $K_i$ value of oGTP for the enzyme was 0.25 mM. Inactivation was prevented by preincubation of the enzyme with GTP, the substrate of the enzyme. At 100% inactivation, 2.3 mol of [8.5'-$^3H$]oGTP were bound per each enzyme subunit, which consists of two identical polypeptides. The active site residue which reacted with the affinity label was lysine. oGTP interacted selectively with the ${\varepsilon}$-amino group of lysine in the GTP-binding site to form a morpholine-like structure which was stable without sodium borohydride treatment. However, triphosphate group was eliminated during the hydrolysis step. To identify the active site of the enzyme, [8.5'-$^3H$]oGTP-labeled enzyme was cleaved by endoproteinase Lys-C, and the $^3H$-labeled peptide was purified by HPLC. The amino acid sequence of the active site peptide was Pro-Ser-Leu-Ser-Lys, which corresponds to the aminoterminal sequence of the enzyme.

• Journal of Life Science
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• v.20 no.10
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• pp.1563-1568
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• 2010

In the course of a research concerning the molecular mechanism of hypocotyl elongation that occurs during soybean seedling growth in darkness, we have generated a number of ESTs from a cDNA library prepared from the hypocotyls of dark-grown soybean seedlings. Comparison of the ESTs assigned a cDNA clone as a putative plastidic ATP-binding-cassette (ABC) protein homologue. The soybean GmNAP1 protein contains an N-terminal transit peptide which targets it into the chloroplast. The transcription level of the GmNAP1 gene was investigated under continuous red light, continuous far-red light, and complete darkness. The main function of this NAP1 protein is the transport of protoporphyrin IX which is the precursor of chlorophyll from the cytoplasm to the chloroplast. The GmNAP1 gene was transferred into the Arabidopsis under the CaMV 35S promoter. The chlorophyll level of this transgenic Arabidopsis plant was much higher than the chlorophyll level of the wild type Arabidopsis plant.

• Animal cells and systems
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• v.8 no.1
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• pp.27-32
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• 2004

Endothellial cells are subjected to hemodynamic shear stress, the dragging force generated by blood flow. Shear stress regulates endothelial cell shape, structure, and function, including gene expression. Since endothelial cells must be anchored to their extracellular matrices(ECM) for their survival and growth, we hypothesized that ECMs are crucial for shear-dependent activation of extracellular signalactivated regulated kinase(ERK) that is important for cell proliferation. Shear stress-dependent activation of ERK was observed in cells plated on two different matrices, fibronectin and vitronectin(the two most physiologically relevant ECM in endothelial cells). We then treated bovine aortic endothelial cells(BAECs) with Arg-Gly-Asp(RGD) peptides that block the functional activation of integrin binding to fibronectin and vitronectin, and a nonfunctional peptide as a control. Treatment of cells with the RGD peptides, but not the control peptide, significantly inhibited ERK activity in a concentration-dependent manner. This supports the idea that integrin adhesion to the ligands, fibronectin and vitronectin, mediates shear stress-dependent activation of ERK. Subsequently, whereas antagonists of vitronectin(LM 609, an antibody for integrin ${\alpha}_{\gamma}$/${\beta}_3$ and XT 199, an antagonist specific for integrin ${\alpha}_{\gamma}$/${\beta}_3$) did not have any effect on shear-dependent activation of ERK, antagonists of fibronectin(a neutralizing antibody for integrin ${\alpha}_5$/${\beta}_1$or ${\alpha}_4$${\beta}_1$ and SM256) had an inhibitory effect. These results clearly demonstrate that mechanoactivation of ERK requires anchoring of endothelial cells to fibronectin through integrins.