• BMB Reports
• /
• v.40 no.6
• /
• pp.1090-1094
• /
• 2007

Melittin (ME), a linear 26-residue non-cell-selective antimicrobial peptide, displays strong lytic activity against bacterial and human red blood cells. To design ME analogue with improved cell selectivity, we synthesized a melittin diastereomer (ME-D) with D-amino acid in the leucine zipper sequence (Leu-6, Lue-13 and Ile-20). Compared to ME, ME-D exhibited the same or 2-fold higher antibacterial activity but 8-fold less hemolytic activity. Circular dichroism analysis revealed that ME-D has much less $\alpha$-helical content in $\alpha$-helical content in the presence of zwitterionic EYPC/cholesterol (10 : 1, w/w) liposomes compared to negatively charged EYPE/EYPG (7 : 3, w/w) liposomes. The blue shift of the fluorescence emission maximum of ME-D in zwitterionic EYPC/cholesterol (10 : 1, w/w) liposomes was much smaller than in negatively charged EYPE/EYPG (7 : 3, w/w) liposomes. These results suggested that the improvement in therapeutic index/cell selectivity of ME-D is correlated with its less permeability to zwitterionic membranes.

• Journal of the Korean Magnetic Resonance Society
• /
• v.13 no.2
• /
• pp.117-125
• /
• 2009

HP0062 is an 86 residue hypothetical protein from Helicobacter pylori strain 26695. HP0062 was identified ESAT-6/WXG100 superfamily protein based on structure and sequence alignment and also contains leucine zipper domain sequence. Here, we report the sequence-specific backbone resonance assignment of HP0062. About 97.7% of all $^1H_N,\;^{15}N,\;^{13}C_{\alpha},\;^{13}C_{\beta}\;and\;^{13}C=O$ resonances were assigned unambiguously. We could predict the secondary structure of HP0062 by analyzing the deviation of the $^{13}C_{alpha}\;and\;^{13}C_{\beta}$ chemical shifts from their respective random coil values. Secondary structure prediction shows that HP0062 consist of two ${\alpha}$-helices. This study is a prerequisite for determining the solution structure of HP0062 and can be used for the study on interaction between HP0062 and DNA and other Helicobacter pylori proteins.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2003.10a
• /
• pp.83.2-83
• /
• 2003

A full length cDNA, OsLEUZIP, encoding leucine zipper containing protein from rice EST of rice (0ryza sativa L. cv. Dongjin) treated Xanthomonas oryzae pv. oryzae 10331. OsLEUZIP contains 1,227 bp nucleotides and encodes a protein of 408 amino acid residues with predicted molecular weight of 47,229 Da. The deduced amino acid sequence of OsLEUZIP has consensus sequence of leucine zipper from PROSITE (PDOC00029), L-X(6)-L-X(6)-L-X(6) -L. OsLEUZIP gene were preferentially induced in rice during incompatible interaction with Xanthomonas oryzae pv. oryzae 10331 and Pyracuraria grisea KJ-301. Expression of OsLEUZIP gene was also induced by treatment of abiotics such as ethephon and ABA. Our data represented in this study suggesting that OsLEUZIP gene may play an important role in the rice defense-related. Further studies of this gene, overexpression in rice, yeast-two hybrid assay, electrophoretic mobility shift assay and northern blot analyses of transgenic plant, would be useful to elucidate the role of the OsLEUZIP gene in defense responses of rice.

• BMB Reports
• /
• v.37 no.2
• /
• pp.139-143
• /
• 2004

The antioxidant responsive element (ARE) is a cis-acting regulatory element of genes encoding phase II detoxification enzymes and antioxidant proteins, such as NAD(P)H: quinone oxidoreductase 1, glutathione S-transferases, and glutamate-cysteine ligase. Interestingly, it has been reported that Nrf2 (NF-E2-related factor 2) regulates a wide array of ARE-driven genes in various cell types. Nrf2 is a basic leucine zipper transcription factor, which was originally identified as a binding protein of locus control region of ss-globin gene. The DNA binding sequence of Nrf2 and ARE sequence are very similar, and many studies demonstrated that Nrf2 binds to the ARE sites leading to up-regulation of downstream genes. The function of Nrf2 and its downstream target genes suggests that the Nrf2-ARE pathway is important in the cellular antioxidant defense system. In support of this, many studies showed a critical role of Nrf2 in cellular protection and anti-carcinogenicity, implying that the Nrf2-ARE pathway may serve as a therapeutic target for neurodegenerative diseases and cancers, in which oxidative stress is closely implicated.

• Journal of Life Science
• /
• v.25 no.8
• /
• pp.947-952
• /
• 2015

Prostate apoptosis response-4 (Par-4) was originally identified in androgen-independent prostate cancer cells undergoing apoptosis. Par-4 is ubiquitously expressed in normal cells and tissues, but it is downregulated in several types of cancers. Par-4 is a 38 kDa tumor suppressor protein encoded by the PARW gene. Par-4 promotes apoptosis in a variety of cancerous cells, but not in normal cells. In this review, we focused on the structure, expression and function of Par-4 in apoptotic signaling pathway. Functional domains of Par-4 include two nuclear localization sequences (NLS), a leucine zipper (LZ) domain, a nuclear export sequence (NES) and selective for apoptosis in cancer cell (SAC) domain. Many studies have underlined the importance of Par-4 in preventing cancer development. The activity of Par-4 is differently regulated by localization of intracellular and extracellular Par-4. Intracellular Par-4 inhibits Akt- and NF-κB-mediated cell survival pathways and downregulates Bcl-2 expression. Extracellular Par-4 activates the extrinsic apoptotic pathway by binding to cell surface receptor GRP78, a stress response protein that is in the endoplasmic reticulum (ER). Endogenous Par-4 sensitizes cancer cells to various apoptotic stimuli, while exogenous Par-4 enhances SAC domain-dependent apoptosis in cancer cells, but not normal cells. Therefore, Par-4 is an attractive target for cancer therapy.

• Development and Reproduction
• /
• v.24 no.2
• /
• pp.101-111
• /
• 2020

Coiled-coil domain containing 110 (CCDC110, KM-HN-1) is a protein containing C-terminal coiled-coil domain (CCD) which was previously discovered as a member of the human cancer/testis antigen (CTA). In addition, CCDC110 has both nuclear localization signal sequence and the leucine zipper motif. Although the functional role of CCDC110 has yet to be fully identified, the mRNA expression levels of CCDC110 are known to be highly elevated in various cancer types including testis, implying its relevance to cancer pathogenesis. In this study, we first developed several monoclonal antibody (mAb) hybridoma clones targeting CCDC110 and further isolated clone by characterizing for its specificity using immunoblotting and immunoprecipitation approaches with basal parenchymal sperm cells in testis tissue. Next, using these mAbs, we showed that the Tet-inducible overexpression of CCDC110 protein delayed the entry of G2/M phase in U2-OS osteosarcoma cells. Based on these results, we propose that CCDC110 plays a crucial role in cell cycle progression.

• Proceedings of the Botanical Society of Korea Conference
• /
• 1996.07a
• /
• pp.40-47
• /
• 1996

The promoters of a variety of plant genes are characterized by the presence of TGACG motif-containing sequences. These genes often exhibit quite diverse expression characteristics and in many case the TGACG-motif has been demonstrated to be essential for expression. Here we report the isolation and characterization of a soybean cDNA that encodes a novel basic/leucine zipper (bZIP) protein, STF1, that specifically interacts with Hex (TGACGTGG) and CRE (TGACGTCA) sequences. This protein contains a bZIP motif at C-teminus and an acidic domain at N-terminus. DNA binding specificities, heterodimer formation, and expression characteristics of STF1 were compared with a soybean TGA1 protein, STGA1. The soybean STF1 interacts with TGACG-sequences containing an ACGT core, while STGA1 requires TGACG as a sufficient binding sequence. The flanking sequences to the TGACG motif affected DNA binding of STF1 siginificantly. The STF1 mRNA is found mainly in dark grown soybean seedling with higher expression in apical and elongating hypocotyl, while STGA1 mRNA is highly abundant in roots of light grown plants. Furthermore, we demonstrate that STF1 heterodimerzes with G-box binding factorss (GBFs) which was not observed with TGA1. The fact that STF1 possesses both distinct DNA binding speficities and heterodimerization properties suggest that STF1 belongs to a new family of plant bZIP proteins which recognize the Hex/CRE motif.

• Journal of Microbiology
• /
• v.45 no.3
• /
• pp.193-198
• /
• 2007

A marine bacterium was isolated from Mai Po Nature Reserve of Hong Kong and identified as Vibrio cholerae MP-1. It contains a small plasmid designated as pVC of 3.8 kb. Four open reading frames (ORFs) are identified on the plasmid, but none of them shows homology to any known protein. Database search indicated that a 440 bp fragment is 96% identical to a fragment found in a small plasmid of another V. cholerae. Further experiments demonstrated that a 2.3 kb EcoRI fragment containing the complete ORF1, partial ORF4 and their intergenic region could self-replicate. Additional analyses revealed that sequence upstream of ORF1 showed the features characteristic of theta type replicons. Protein encoded by ORF1 has two characteristic motifs existed in most replication initiator proteins (Rep): the leucine zipper (LZ) motif located at the N-terminal region and the alpha helix-turn-alpha helix motif (HTH) located at the C-terminal end. The results suggest that pVC replicates via the theta type mechanism and is likely a novel type of theta replicon.

• Journal of Animal Science and Technology
• /
• v.50 no.2
• /
• pp.265-272
• /
• 2008

The CCAAT/enhancer binding protein β(C/EBPβ), a member of the leucine zipper DNA-binding protein of transcription factor, plays a crucial role in the control of early phases of adipocyte differentiation. In this studies, we report the identification, characterization, and expression of the Korean native cattle C/EBPβ gene. The Korean native cattle and black cattle C/EBPβ cDNA includes a 1047bp open reading frame encoding a protein of 348 amino acids. The C/EBPβ cDNA sequence of the Korean native cattle and black cattle shows high conservation with the corresponding amino acid sequences reported in other species. The distribution of C/EBPβ mRNA in various tissues of Korean native cattle aged 26 months was investigated using Northern Blot analysis. The C/EBPβ expression was detected in adipose tissue, lung, sirloin while expression was not detected in heart, kidney, small intestine, colon, and liver. However, we are analyzed polymorphism of bZIP domain in the C/EBPβ gene. A polymorphism was not identified at this position.

• Korean Journal of Plant Tissue Culture
• /
• v.24 no.1
• /
• pp.1-35
• /
• 1997

Fertilized egg, by successive cell divisions, differentiates into different tissues and organs with various structures and functions. Different cells and tissues contain different proteins, products of selective gene expression. Not all the genes in any genomes are equally active, temporal and spatial gene expression being the general rule. Present paper attempts to review the tanscriptional mechanisms or the initiations of transcription from several angles. In some of the organisms the genes in the process of transcription or the genes in the inactive state can be seen under the light microscope. Some bands of Drosophila polytene chromosomes may exhibit a swollen or puff appearance under certain conditions. A puff, unfolded or decondensed form of chromomere, represents sets of intense transcriptional activity or RNA synthesis. The heterochromatic X chromosome whose genes remain inactive in the female mammals can be visualized as a dark staining structure called Barr body, Configuration of chromatin differs between transcribed and nontranscribed chromatin. Modification to the chromatin facilitates RNA synthesis. The movement of large polymerase molecule along the DNA would probably be facilitated if some modifications of the chromatin configuration is effected. Methylation of cytosines in CG sequences is associated with inactive genes. Methylation can play a role in determination of mammalian cells during embryogenesis. Demethylation is necessary for the gene to be expressed during development A histone modification that is also known to be correlated with transcriptional capacity of chromatin is acetylation of the lysine residues of the core histones. Chromatin containing a high level of histone acetylation is very sensitive to DNase 1. For the transcription to occur TBP must first bind to the TATA box. Another TF, TF IIB, then binds to the promoter-TBP complex, facilitating the access of RNA polymerase to the transcription initiation site. As recently as eight years ago researchers assumed that histones were irrelevant to the regulation of gene expression. Histones combine with the DNA to form nucleosome of the chromatin. Histones are vital participant in gene regulation. Histone and basal factors compete for access to TATA box. When DNA is exposed to basal factors before histones are introduced, the basal factors assemble on TATA boxes preventing the access of histones, allowing transcription to occur, for transcription to begin, activator protein at the upstream activation sequence or enhancer must interact with the tail of histone H4 at TATA box and cause the histone role particle to dissociate from the TATA box leading to partial breakup of the histone core particle and allowing the basal factors to bind to the TATA box. New concept of genomic flux in contrast to the old concept of static genome has been developed based on the powerful new molecular techniques. Genomic changes such as repetitive DNAs and transposable elements, it is assumed but not yet proved, may affect some of the developmental patterns that characterize particular cells, tissues, organs, and organisms. In the last decade or so remarkable achievement have been made in the researches of the structures and functions of TFs and the specific target sequences located in promoters or enhancers where these TFs bind. TFs have independent domains that bind DNA and that activate transcription. DNA binding domain of TFs serves to bring the protein into the right location. There are many types of DNA binding domains. Common types of motifs can be found that are responsible for binding to DNA. The motifs are usually quite short and comprise only a small part of the protein structure. Steroid receptors have domains for hormone binding, DNA binding, and activating transcription. The zinc finger motif comprises a DNA binding domain. Leucine zipper consist of a stretch of amino acids with a leucine residue in every seventh position Two proteins form a dimer because they interact by means of leucine zippers on similar α-helical domain. This positions their DNA binding basic domains for interaction with the two halves of a DNA sequence with dyad symmetry of TGACTCA, ACTGAGT.