• Ocean and Polar Research
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• v.25 no.4
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• pp.607-615
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• 2003

Many organisms are known to survive in icy environments. These include both over wintering terrestrial insects and plants as well the marine fish inhabiting high latitudes. The adaptation of these organisms is both a fascinating and important topic in biology. Marine teleosts in particular, can encounter ice-laden seawater that is approximately $1^{\circ}C$ colder than the colligative freezing point of their body fluids. These animals produce a unique group of proteins, the antifreeze proteins (AFPs) or antifreeze glycoproteins (AFGPs) that absorb the ice nuclei and prevent ice crystal growth. Presently, there are at least four different AFP types and one AFGP type that are isolated from a wide variety of fish. Despite their functional similarity, there is no apparent common protein homology or ice-binding motifs among these proteins, except that the surface-surface complementarity between the protein and ice are important for binding. The remarkable diversity of these proteins and their odd phylogenetic distribution would suggest that these proteins might have evolved recently in response to sea level glaciations just 1-2 million years ago in the northern hemisphere and 10-30 million years ago around Antarctica. Winter flounder, Pleuronectes americanus, has been used as a popular model to study the regulation of AFP gene expression. It has a built-in annual cycle of AFP expression controlled negatively by the growth hormone. The signal transduction pathways, transcription factors and promoter elements involved in this process have been studied in our laboratory and these studies will be presented.

• Microbiology and Biotechnology Letters
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• v.16 no.5
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• pp.389-392
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• 1988

A clone pSL 2-1, which is a recombinant plasmid believed to contain the mosquitocidal crystal-line protein gene of the Bacillus sphaericus 1593, was expressed in Escherichia coli JM83 and the product of the clone was purified and identified. The unsolubilized mosquitocidal crystal proteins from the B. sphaericus had formed 43, 58, 64, 100, 113, and 130 Kd bands in the SDS-polyacrylamide gel, but the NaOH-solublized proteins at pH 12 formed 2 protein bands of 43- and 64Kd in the gel because the larger protein (precursor) bands were cleaved. The products of the pSL 2-1 clone was purified by Sephadex G-200 and only the fractions having lethal activity to the 3rd in-star larvae of mosquito Culex pipiens were analyzed by the gel. The only single protein band of 42 Kd toxic to the larvae was formed. The major toxic protein being produced from the B. sphaericus 1593 and the pSL 2-1 clone was found to be the 42 Kd.

• Molecules and Cells
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• v.38 no.8
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• pp.715-722
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• 2015

In Gram-negative bacteria in the periplasmic space, the dimeric thioredoxin-fold protein DsbC isomerizes and reduces incorrect disulfide bonds of unfolded proteins, while the monomeric thioredoxin-fold protein DsbA introduces disulfide bonds in folding proteins. In the Gram-negative bacteria Salmonella enterica serovar Typhimurium, the reduced form of CueP scavenges the production of hydroxyl radicals in the copper-mediated Fenton reaction, and DsbC is responsible for keeping CueP in the reduced, active form. Some DsbA proteins fulfill the functions of DsbCs, which are not present in Gram-positive bacteria. In this study, we identified a DsbA homologous protein (CdDsbA) in the Corynebacterium diphtheriae genome and determined its crystal structure in the reduced condition at $1.5{\AA}$ resolution. CdDsbA consists of a monomeric thioredoxin-like fold with an inserted helical domain and unique N-terminal extended region. We confirmed that CdDsbA has disulfide bond somerase/reductase activity, and we present evidence that the N-terminal extended region is not required for this activity and folding of the core DsbA-like domain. Furthermore, we found that CdDsbA could reduce CueP from C. diphtheriae.

• Molecules and Cells
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• v.43 no.12
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• pp.1035-1045
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• 2020

The Drosophila genome contains four low molecular weight-protein tyrosine phosphatase (LMW-PTP) members: Primo-1, Primo-2, CG14297, and CG31469. The lack of intensive biochemical analysis has limited our understanding of these proteins. Primo-1 and CG31469 were previously classified as pseudophosphatases, but CG31469 was also suggested to be a putative protein arginine phosphatase. Herein, we present the crystal structures of CG31469 and Primo-1, which are the first Drosophila LMW-PTP structures. Structural analysis showed that the two proteins adopt the typical LMW-PTP fold and have a canonically arranged P-loop. Intriguingly, while Primo-1 is presumed to be a canonical LMW-PTP, CG31469 is unique as it contains a threonine residue at the fifth position of the P-loop motif instead of highly conserved isoleucine and a characteristically narrow active site pocket, which should facilitate the accommodation of phosphoarginine. Subsequent biochemical analysis revealed that Primo-1 and CG31469 are enzymatically active on phosphotyrosine and phosphoarginine, respectively, refuting their classification as pseudophosphatases. Collectively, we provide structural and biochemical data on two Drosophila proteins: Primo-1, the canonical LMW-PTP protein, and CG31469, the first investigated eukaryotic protein arginine phosphatase. We named CG31469 as DARP, which stands for Drosophila ARginine Phosphatase.

• International Journal of Industrial Entomology and Biomaterials
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• v.1 no.2
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• pp.115-122
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• 2000

A Bacillus thuringiensis designated NT0423, belonging to B. thuringiensis subsp. aizawai (H 7), was isolated from samples of dust and soil of sericultural farms. B. thuringiensis NT0423 having dualspecificity against Lepidoptera and Diptera produced bipyramidal inclusions consisting of two major polypeptides of approximately 130- and 70-kDa. Proteolytic processing by trypsin and gut juice of Bombyx mori yielded predominant proteins with molecular masses of about 66-kDa. The whole crystal protein of B. thuringiensis NT0423 immunologically was related to that of B. thuringiensis subsp. aizawai. PCR analysis showed that B. thuringiensis NT0423 has at least five crystal protein genes including cryIA(a), cryIA(b), cryIC, cryID and cryIIA, and southern blot was determined the location of each gene on intact and enzyme-digested plasmid DNA fragments. Except for cryIA(a) gene on the high molecular weight plasmid of 165-kb, all of four genes were located on the plasmid of 66-kb. The production of $\beta$-exotoxin from B. thuringiensis NT0423 was identified by the HPLC analysis. In addition, the $\beta$-exotoxin showed its ability to prevent pupation of treated larvae of house flies (Musca domestica) from developing into normal adults.

• Journal of Photoscience
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• v.9 no.2
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• pp.362-363
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• 2002

Since chlorophyll a and bacteriochlorophyll a are asymmetric molecules, an external ligand can coordinate to the central Mg atom either from the chiorin macrocycle side where the C13$^2$-methoxycarbonyl moiety protrudes (denoting as the 'back' side) or frome the other side (the 'face' side). We investigated which side of the macrocycle is favored for the ligand coordination, by survey of the highly resolved crystal structures of various photosynthetic proteins and theoretical model calculations. It is found that chlorophyll a as well as bacteriochlorophyll a and b in the photosynthetic proteins mostly bind their ligands on the 'back' sides. This finding was confirmed by the theoretical calculations for methyl chlorophyllide a and methyl bacteriochlorophyllide a as models: the 'back' type ligand-(bacterio )chlorophyll complex was more stable than the 'face' type one. The calculations predicted influence of the Cl3$^2$-stereochemistry on the choice of the side of the ligand coordination, which is discussed in relation to the presence of the Cl3$^2$-epimer of chlorophyll a in photosystem I reaction center [I].

• Biomolecules & Therapeutics
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• v.25 no.1
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• pp.4-11
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• 2017

Heterotrimeric G proteins are key intracellular coordinators that receive signals from cells through activation of cognate G protein-coupled receptors (GPCRs). The details of their atomic interactions and structural mechanisms have been described by many biochemical and biophysical studies. Specifically, a framework for understanding conformational changes in the receptor upon ligand binding and associated G protein activation was provided by description of the crystal structure of the ${\beta}2$-adrenoceptor-Gs complex in 2011. This review focused on recent findings in the conformational dynamics of G proteins and GPCRs during activation processes.

• Proceedings of the Korean Biophysical Society Conference
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• 1996.07a
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• pp.9-9
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• 1996

The immunosuppressive and cell cycle arrest agent rapamycin works by binding together two proteins: the FK506 binding protein (FKBP12) and the FKBP-rapamycin associated protein (FRAP). A 2.7 $\AA$ resolution crystal structure of the triple complex of human FK506 binding protein (FKBP12), rapamycin, and FKBP12-rapamycin binding domain (FRB) of FRAP, reveals two proteins bound together through rapamycin' s ability to simultaneously occupy two different hydrophobic binding pockets. (omitted)

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.21-21
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• 2001

PDZ domains are molecular-recognition elements that mediate protein-protein interactions. The PDZ domain was discovered originally as a common motif present in three structurally related proteins： PSD-95 (postsynaptic density protein), Dlg (discs-large protein) and ZQ-1 (zonula occludens-1). The PDZ domain is globular domain, containing about 80-100 amino acids, and a conserved motif with two alpha helices and six beta strands. Most of them bind selectively to the C-termini of the interacting proteins at the complexes of signaling molecules and membrane associated receptors.(omitted)

• Biodesign
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• v.6 no.4
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• pp.92-95
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• 2018

API5 is a unique oncogenic, non-BIR type IAP nuclear protein and is up-regulated in several cancers. It exerts several functions, such as apoptosis inhibition, cell cycle progression, cancer immune escape, and anticancer drug resistance. Although structural studies of API have revealed that API5 mediates protein-protein interactions, its detailed molecular functions remain unknown. Since FGF2 is one of API5's major interacting proteins, structural studies of the API5-FGF2 complex will provide insight into both proteins' molecular function. We overexpressed and purified API5 and FGF2 in Escherichia coli and crystallized the API-FGF2 complex using polyethylene glycol (PEG) 6000 as a precipitant. Diffraction data were collected to a $2.7{\AA}$ resolution using synchrotron X-rays. Preliminary diffraction analysis revealed that the API5-FGF2 complex crystal belongs to the space group $P2_12_12_1$ with the following unit cell parameters: a = 46.862, b = 76.523, $c=208.161{\AA}$. One asymmetric unit with 49.9% solvent contains one API5-FGF2 complex. Molecular replacement calculation, using API5 and FGF2 coordinates, provided a clear electron density map for an API5-FGF2 complex.