• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.4-4
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• 2002

PDZ domains bind to short segments within target proteins in a sequence-specific fashion. GRIP/ABP family proteins contain six to seven PDZ domains and interact via its sixth PDZ domain (class Ⅱ) with the C-termini of various proteins, including liprin-α. In addition the PDZ456 domain mediates the formation of homo- and heteromultimers of GRIP proteins. To better understand the structural basis of peptide recognition by a class Ⅱ PDZ domain and DZ-mediated multimerization, we determined the crystal structures of the GRIPI PDZ6 domain, alone and in complex with a synthetic C-terminal octapeptide of human liprin-α, at resolutions of 1.5 Å and 1.8 Å, respectively. Remarkably, unlike other class Ⅱ PDZ domains, Ile736 at αB5 rather than conserved Leu732 at αB1 makes a direct hydrophobic contact with the side chain of the Tyr at the -2 position of the ligand. Moreover, the peptide-bound structure of PDZ6 shows a slight reorientation of helix αB, indicating that the second hydrophobic pocket undergoes a conformational adaptation to accommodate the bulkiness of the Tyr's side chain, and forms an antiparallel dimer through an interface located at a site distal to the peptide-binding groove. This configuration may enable formation of GRIP multimers and efficient clustering of GRIP-binding proteins.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1756-1762
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• 2007

Envelope proteins of virus contain a segment of hydrophobic amino acids, called as fusion peptide, which triggers membrane fusion by insertion into membrane and perturbation of lipid bilayer structure. Potential fusion peptide sequences have been identified in the middle of L or M proteins or at the N-terminus of S protein in the envelope of human hepatitis B virus (HBV). Two 16-mer peptides representing the N-terminal fusion peptide of the S protein and the internal fusion peptide in L protein were synthesized, and their membrane disrupting activities were characterized. The internal fusion peptide in L protein showed higher activity of liposome leakage and hemolysis of human red blood cells than the N-terminal fusion peptide of S protein. Also, the membrane disrupting activity of the extracellular domain of L protein significantly increased when the internal fusion peptide region was exposed to N-terminus by the treatment of V8 protease. These results indicate that the internal fusion peptide region of L protein could activate membrane fusion when it is exposed by proteolysis.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.399-405
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• 1998

From the sequence alignment of various non-ribosomal peptide synthetases, several motifs of highly conserved sequences have been identified within each domain of peptide synthetases. We designed PCR primers based on the highly conserved nucleotide sequences to amplify and isolate a ∼7.2-kb DNA fragment of the Bacillus subtilis 713 which was isolated and reported to produce an antifungal peptide compound. Nucleotide sequence analysis of 4.8 kb of the predicted amino acids revealed significant homology to various peptide synthetases over the whole sequence and also revealed two amino acid-activating domains with highly conserved Core 1 to Core 6 and spacer motif. This suggests that the isolated DNA fragment is part of a peptide synthetase gene for antifungal peptide.

• BMB Reports
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• v.31 no.6
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• pp.536-541
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• 1998

The cDNA clone encoding the antibacterial peptide (SL-1) was isolated from the fat body of the common cutworm, Spodoptera litura, immunized with E. coli K12. The primary structure analysis revealed that its deduced amino acid sequence showed the characteristics of the cecropin family antibacterial peptides and that the amino acid residues highly conserved in the antibacterial peptides from moths and flies were also conserved, implying that SL-1 was a cecropin-like, and especially cecropin B-like, peptide. The predicted secondary structure of the mature SL-1 consists of three domains: (i) an amphiphilic ${\alpha}$-helical domain (Ile-4 to Gly-18); (ii) the hinge region (Gly-23 and Pro-24); and (iii) a hydrophobic domain (Ala-25 to IIe-38).

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.227-231
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• 1998

The teleosts represent ancient real-bony vertebrates in phylogeny and resemble major genetic patterns to higher vertebrates. In the present study, we have defined the single family of insulin-like growth factors (IGFs) from flounder (Paralichthys olivaceus), compared to the prototype of IGFs observed in the Agnathan hagfish. In flounder, IGFs are clearly diverged into two major types including type I and II, and they are structurally similar by displaying a multidomain structure consisting of five functional regions as previously found in other vertebrates. However, flIGF-I appears to be more basic (pI 8.03) than the flIGF-II (pI 5.34) in the fully processed form for the B to D domain region. The flIGF-I seems to contain an evolutionary conserved Asn-linked glycosylation in E domain, which is not found in flIGF­II. The most interesting feature is that flIGF-II appeared to be structurally close to hagfish IGF in secondary structures, particularly in Band D domains. This could tell us an idea on the molecular divergence of IGFs from the Agnatha to teleosts during the vertebrate phylogeny. It also support, in part, a notion regarding on how IGF-II is appeared as more embryonic during development. Nonetheless, the biologically active B to D domain region of flIGF-II shows significant sequence homology of $65.6\%$ to flIGF-Is and contains the evolutionary conserved insulin-family signature, as well as a reserved recognition site (Lys) in D domain, necessary to generate proteolytic cleavage for E-peptide. A significant structural difference was found in E domain in which flIGF-I possesses two potential alternative splicing donor site at $Val^{17,\;24}$ of E domain. Therefore, it seems so far that IGF-I sorely produces spliced variants due to the spliced E-peptide moiety while IGF-II appears to be maintained in a single type during evolution. IGF-II, however, may be also possible to transcribe unidentified variants, depending on the physiological conditions of tissues in vertebrates in vivo.

• BMB Reports
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• v.28 no.2
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• pp.87-93
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• 1995

To investigate the biological functions of the EGF-like domain of mouse betacellulin (BTC), mouse BTC(33-80), a 48-residue peptide corresponding to the EGF-like domain, was synthesized by stepwise solidphase methods using a 9-fluorenylmethoxycarbonyl (Fmoc) strategy. The homogeneity of synthetic mouse BTC(33-80) was confirmed by analytical reversed phase (RP)-HPLC, amimo acid analysis, and fast atom bombardment mass spectrometer (FAB-MS). Three disulfide bond pairings of synthetic mouse BTC(33-80) were established by amino acid analysis of cysteine-containing fragments derived from thermolytic digestion. These were consistent with the pairings of EGF and transforming growth factor ($TGF-{\alpha}$). The EGF-Iike domain of mouse BTC showed equipotent activity in both EGF-receptor binding on A-431 epidermoid carcinoma cells, and mitogenesis on NIH-3T3 fibroblast cells, as compared with authentic h-EGF. Results suggest that the EGF-Iike domain of BTC plays a significant role in mitogenic activity with an EGF-receptor mediated system.

• Molecules and Cells
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• v.25 no.3
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• pp.352-357
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• 2008

Osteoprotegerin (OPG) is a soluble decoy receptor that inhibits osteoclastogenesis and is closely associated with bone resorption processes. We have designed and determined the solution structures of potent OPG analogue peptides, derived from sequences of the cysteine-rich domain of OPG. The inhibitory effects of the peptides on osteoclastogenesis are dose-dependent ($10^{-6}M-10^{-4}M$), and the activity of the linear peptide at $10^{-4}M$ is ten-fold higher than that of the cyclic OPG peptide. Both linear and cyclic peptides have a ${\beta}$-turn-like conformation and the cyclic peptide has a rigid conformation, suggesting that structural flexibility is an important factor for receptor binding. Based on structural and biochemical information about RANKL and the OPG peptides, we suggest that complex formation between the peptide and RANKL is mediated by both hydrophobic and hydrogen bonding interactions. These results provide structural insights that should aid in the design of peptidyl-mimetic inhibitors for treating metabolic bone diseases caused by abnormal osteoclast recruitment.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.310-317
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• 1998

Peptide synthetases are large multifunctional enzyme complexes that catalyze the nonribosomal synthesis of a structurally diverse family of peptide antibiotics. These enzymes are composed of functionally independent domains with independent enzymatic activities. Their specific linkage order of domains forms the protein template that defines the sequence of the incorporated amino acids. Within each domain, several motifs of highly conserved sequences have been identified from the sequence alignment of the various peptide synthetases ［30］. Taking advantage of the conserved nucleotide sequence of Core 1 and Core 2, we designed PCR primers to amplify the peptide synthetase genes from three different gram-positive bacterial strains. Nucleotide sequence analysis of the amplified PCR products from those three strains showed significant homology to various peptide synthetase genes, suggesting that the PCR products are parts of peptide synthetase genes. Therefore, this rapid and efficient PCR technique can be used for the isolation of peptide synthetase genes from various strains.

• International Journal of Industrial Entomology and Biomaterials
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• v.37 no.2
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• pp.49-54
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• 2018

To artificially enhance antimicrobial peptide expression in Bombyx mori, we constructed genetically engineered silkworms overexpressing Rel family transcription factor. The truncated BmRelish1 (BmRelish1t) gene contained a Rel homolog domain (RHD), nuclear localization signal (NLS), acidic and hydrophobic amino acid (AHAA)-rich region, and death domain (DD), but no ankyrin-repeat (ANK) domain. The BmRelish1t gene was controlled by B. mori cytoplasmic actin 3 promoter in the PiggyBac transposon vector. Chromosome analysis of G1 generations of a transgenic silkworm with EGFP expression confirmed stable insertion of BmRelish1t. BmRelish1t gene overexpression in transgenic silkworms resulted in higher mRNA expression levels of B. mori antimicrobial peptides such as lebocin(~20.5-fold), moricin(~8.7-fold), and nuecin(~17.4-fold) than those in normal silkworms.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.117-124
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• 1994

Phospholamban is the regulator of $Ca^{2+}-ATPase$ in cardiac sarcoplasmic reticulum(SR). The mechanism of regulation appears to involve inhibition by dephosphorylated phospholamban. Phosphorylation of phospholamban relieves this inhibition. Recently, there has been a report that the cytoplasmic domain (amino acids 1-25) of phospholamban is insufficient to inhibit the $Ca^{2+}$ pump. To explore the domains of phospholamban responsible for $Ca^{2+}-ATPase$ inhibitory activity, we examined the effect of a synthetic phospholamban peptide consisting of amino acid residues 1-25 on $Ca^{2+}$ uptake by reconstituted skeletal SR $Ca^{2+}-ATPase$. The $Ca^{2+}-ATPase$ of skeletal SR was purified and reconstituted in proteoliposomes containing phosphatidylcholine (PC) or phosphatidylcholine: phosphatidylserine (PC:PS). Inclusion of a phospholamban peptide in PC proteoliposomes was associated with significant inhibition of the initial rates of $Ca^{2+}$ uptake at pCa 6.0, and phosphorylation of this peptide by the catalytic subunit of cAMP-dependent protein kinase reversed the inhibitory effect on the $Ca^{2+}$ pump. Similar effects of phospholamban peptide were also observed using PC:PS proteoliposomes. Based on these results, we could conclude that the cytoplasmic domain of phospholamban, containing the phosphorylation sites, by itself is sufficient to inhibit the $Ca^{2+}$ pump of SR.