• KSBB Journal
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• v.16 no.1
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• pp.1-10
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• 2001

Escherichia coli has been used as an expression work horse for foreign genes. This article summarized recent development in genetic engineering techniques for overproduction of medical proteins and industrial enzymes. Special emphasis was placed upon research activities concerning folding and refolding of inclusion bodies at genetic and fermentation levels. Plasmid and mRNA stabilization, development of strong inducible promoters, modification of translational elements and reduction of rpoteolytic degradation were carried out to elevate an expression level of a target protein. Optimization of culture conditions, improvement of denaturation and renaturation steps and coexpression of molecular chaperones or foldase were accomplished to produce active proteins in soluble form. Fusion protein systems with selective separation and surface display technology were also performed in an effort to make the E. coli expression system more effective and versatile.

• Molecules and Cells
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• v.19 no.2
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• pp.157-166
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• 2005

Transfer RNA (tRNA) is a key molecule to decode the genetic information on mRNA to amino aicds (protein), in a ribosome. For tRNA to fulfill its adopter function, tRNA should be processed into the standard length, and be post-transcriptionally modified. This modification step is essential for the tRNA to maintain the canonical L-shaped structure, which is required for the decoding function of tRNA. Otherwise, it has recently been proposed that modification procedure itself contributes to the RNA (re)folding, where the modification enzymes function as a kind of RNA chaperones. Recent genome analyses and post-genome (proteomics and transcriptomics) analyses have identified genes involved in the tRNA processings and modifications. Furthermore, post-genomic structural analysis has elucidated the structural basis for the tRNA maturation mechanism. In this paper, the recent progress of the structural biology of the tRNA processing and modification is reviewed.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.2
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• pp.496-499
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• 2004

We have previously observed that Bambusae Caul is in Liquamen (BCL) stimulates the adipose conversion of 3T3-L1 cells and molecular chaperones were involved in the process of the assembly and replacement of laminin subunits in Bovine aortic endothelial cells(BAEC). Endothelial cells are exposed to continuous shear stress due to the blood flow. Heat shock protens(hsp) are a well-known stress response protein, namely, stress proteins. To investigate effects of BCL on the stress proteins induced by heating in endothelial cells, we have analyzed synthetic amounts of stress proteins in sodium dodecyl sulfate gel electrophoresis under reducing conditions. Under the condition of heating stress, BCL inhibited the synthesis of stress proteins in endothelial cells. These results suggest that BCL may have an important role for expression of stress proteins induced by heating in endothelial cells.

• Genomics & Informatics
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• v.11 no.1
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• pp.52-54
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• 2013

Proteins in DNAJ/K families are ubiquitous, from prokaryotes to eukaryotes, and function as molecular chaperones. For systematic phylogenomics of the DNAJ/K families, we developed the Eukaryotic DNAJ/K Database (EDD). A total of 12,908 DNAJs and 4,886 DNAKs were identified from 339 eukaryotic genomes in the EDD. Kingdom-wide comparison of DNAJ/K families provides new insights on the evolutionary relationship within these families. Empowered by 'class', 'cluster', and 'taxonomy' browsers and the 'favorite' function, the EDD provides a versatile platform for comparative genomic analyses of DNAJ/K families.

• The Journal of Korean Physical Therapy
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• v.12 no.1
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• pp.147-151
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• 2000

Heat shock protein 70(HSP70) is induced by elevated temperature and many other types of stresses in cell. HSP70 ensures cell survival under stressful condition that would lead to irreversible cell damage and ultimately to cell death. HSP70 plays essential role in the synthesis, transport, and folding of proteins and is often refferred to as molecular chaperones. Increased levels of HSPs occur after arthritis, infection, imflammation, autoimmune disease and CNS injury such as infarction, ischemia, seizure and Alzheimer's disease. Also, HSP70 increases resistance to apoptosis. The recent studies that the expression of the HSP has been processed at various field. However, they an still relatively line studied in clinically application. This review summarizes the fundamental knowledge of HSP.

• Animal cells and systems
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• v.7 no.3
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• pp.271-277
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• 2003

Regulation of endoplasmic reticulum(ER) chaperone, ERp29, in traumatized rat spinal cord was investigated. Compared to the control, ERp29 expression was down-regulated at the lesion site 1 d after spinal cord injury. However, ERp29 expression gradually increased from 3 d after the injury and peaked remarkably after 7 d. Two ER chaperones (GRP94 and BiP) showed constantly strong expression levels 1 d after spinal cord injury while the expression levels of the other two (calnexin and PDI) were unchanged. In the case of ERp72, its expression level was increased 1 d after the injury and gradually decreased thereafter. This study suggests that ERp29 expression in the spinal cord after traumatic injury might be associated with the posttraumatic neural survival, playing a role as a molecular chaperone.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2003.10a
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• pp.112-112
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• 2003

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2508-2512
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• 2012

Cold shock proteins (CSPs) are a family of proteins induced at low temperatures. CSPs bind to single-stranded nucleic acids through the ribonucleoprotein 1 and 2 (RNP 1 and 2) binding motifs. CSPs play an essential role in cold adaptation by regulating transcription and translation via molecular chaperones. The solution nuclear magnetic resonance (NMR) or X-ray crystal structures of several CSPs from various microorganisms have been determined, but structural characteristics of psychrophilic CSPs have not been studied. Therefore, we optimized the purification process to obtain highly pure Lm-Csp and determined the three-dimensional structure model of Lm-Csp by comparative homology modeling using MODELLER on the basis of the solution NMR structure of Bs-CspB. Lm-Csp consists of a ${\beta}$-barrel structure, which includes antiparallel ${\beta}$ strands (G4-N10, F15-I18, V26-H29, A46-D50, and P58-Q64). The template protein, Bs-CspB, shares a similar ${\beta}$ sheet structure and an identical chain fold to Lm-Csp. However, the sheets in Lm-Csp were much shorter than those of Bs-CspB. The Lm-Csp side chains, E2 and R20 form a salt bridge, thus, stabilizing the Lm-Csp structure. To evaluate the contribution of this ionic interaction as well as that of the hydrophobic patch on protein stability, we investigated the secondary structures of wild type and mutant protein (W8, F15, and R20) of Lm-Csp using circular dichroism (CD) spectroscopy. The results showed that solvent-exposed aromatic side chains as well as residues participating in ionic interactions are very important for structural stability. Further studies on the three-dimensional structure and dynamics of Lm-Csp using NMR spectroscopy are required.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1925-1930
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• 2011

Psychrophilic bacteria have acquired cold-resistance in order to protect themselves against freezing temperatures, which would otherwise be lethal. DnaK/DnaJ/GrpE systems are molecular chaperones which facilitate proper folding of newly synthesized proteins. Efficient folding processes are of great importance especially in a cold environment, such as the Arctic. In order to understand the protection mechanisms of psychrophilic bacteria against cold temperatures, we have explored a genome of KOPRI22215, tentatively identified as Psychromonas arctica, whose genome sequence has not yet been discovered. With an aim of searching for a coding gene of DnaK from KOPRI22215, we have applied a series of polymerase chain reactions (PCR) with homologous primers designed from other Psychromonas species and LA PCR in vitro cloning. 1917 bp complete coding sequence of dnaK from KOPRI22215 was identified including upstream promoter sites. Recombinant plasmids to overexpress PaDnaK along with EcDnaK (DnaK of E. coli) were then constructed in pAED4 vector and the pET-based system to induce PaDnaK expression by IPTG. Characterization assays of expressed PaDnaK were carried out by measuring survival rates upon 4 day incubation at 4 $^{\circ}C$: a refolding assay as molecular chaperone, and ATPase assay for functional activity. Taking account of all the data together, we conclude that PaDnaK was identified, successfully expressed, and found to be more efficient in providing cold-resistance for bacterial cells.

• Journal of Life Science
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• v.11 no.5
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• pp.464-469
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• 2001

A gene, dnaK2, encoding a distinct member of the HSP70 family of molecular chaperones is isolated from the halotolerant cyanobactrium Aphanothece halophytica. The dnak2 gene encodes a molecular wight of 68 kDa polypeptide with predicted 616 amino acid residues. The DnaK2 protein has a structural characteristic of bacterial DnaK homologues and shows high similarity to other HSP70/Dank proteins. The danK2 transcripts are hardly detectable at 28$^{\circ}C$ and strongly induced upon heat stress. It is also found that dnaK2 transcript is increased by high-salinity stress even in the absence of heat stress. These results suggest that the DnaK2 protein plays an important role in protecting A. halophytica against damage caused by salt stress at well as heat stress.