• Journal of Microbiology and Biotechnology
• /
• v.18 no.2
• /
• pp.328-333
• /
• 2008

A series of pep tides binding to the HCV NS5B polymerase was selected from phage display peptide libraries. A conserved motif of Ser-Arg-X-Arg/Leu was identified among the selected peptides, and Pep2 (Trp-Ser-Arg-Pro-Arg-Ser-Leu) was chosen for further characterization. The binding of Pep2 to HCV NS5B in vivo was shown by a yeast two-hybrid assay and by subcellular colocalization analysis using immunofluorescence confocal microscopy. The in vitro interaction was also confirmed by GST pulldown assay. The replication of the HCV 1b subgenomic replicon was efficiently inhibited by the presence of the peptide. By using a subtractive biopanning against Pep2, the binding site of the peptide was mapped at the pocket of Pro388 to Pro391 in the thumb subdomain of the polymerase. A yeast two-hybrid analysis using Pro388Ala and Pro391Ala mutants of NS5B confirmed the binding.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.12
• /
• pp.4337-4340
• /
• 2011

The vitamin D receptor binding peptide, VDRBP, was overexpressed as a fused form with the ubiquitin molecule in Rosetta(DE3)pLysS, a protein production strain of Escherichia coli harboring an induction controller plasmid. The fusion protein was bound to the immobilized metal ions, and the denaturation and renaturation of the fusion protein were performed as a part of the purification procedure. After the elution of the fusion protein, the peptide hormone was released from its fusion partner by using yeast ubiquitin hydrolase (YUH), and subsequently purified by reverse phase chromatography. The purity of the resulting peptide fragment was checked by MALDI-TOF mass and NMR spectroscopy. The final yields of the target peptide were around 5 and 2 mg per liter of LB and minimal media, respectively. The recombinant expression and purification of this peptide will enable structural and functional studies using multidimensional NMR spectroscopy and X-ray crystallography.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.84-84
• /
• 2013

FcBP consisting of 13 amino acids specifically binds to Immunoglobulin G Fc domain. Initially, we utilized this peptide for preparation of antibody chip as a PEG composite for enhanced solubility. After then, the peptide conjugate was immobilized on agarose resin, resulting in highly efficient affinity column for antibody purification. The efficiency was comparable to commercial Protein A column. Recently, this peptide was conjugated with cell penetratingpeptide (CPP) on a backbone of GFP, affording antibody transducer, which carries antibody into live cells by simple mixing of antibody and the transducer in cell culture media. Antibody transduction into cells was monitored by live cell imaging. More recently, the FcBP was fused to ferritin cage, which consists of 24 ferritin protein molecules. The FcBP-ferritin cage showed greatly increased binding affinity to human IgG. Its binding was analyzed by QCM and SPR analysis. Finally, it was selectively delivered by Herceptin to SKBR3, a breast cancer cell, over MCF10A, non-tumorigenic cells.

• KSBB Journal
• /
• v.28 no.3
• /
• pp.185-190
• /
• 2013

For the selection of peptide specifically binding to $Pb^{2+}$, the biopanning with the commercially available Ph.D.-7 phage displayed heptapeptide library was carried out against $Pb^{2+}$ immobilized on a metal-chelating IDA (iminodiacetic acid) resin. After four rounds of screening against $Pb^{2+}$-IDA including negative selections against charged bead with metal ions other than $Pb^{2+}$ and uncharged bead, several candidate lead-binding phage peptides were initially determined based on the order of frequency from the screened phage clones. Of the selected phage peptide sequences, the peptide of the highest frequency, CysSerIleArgThrLeuHisGlnCys (CSIRTLHQC) also exhibited the strongest affinity for $Pb^{2+}$ in binding assays for individual phage clones. However, there was not a significant difference in $Pb^{2+}$ affinity between selected peptides when using synthetic heptapeptides corresponding to the displayed peptide sequences of phage clones.

• BMB Reports
• /
• v.29 no.2
• /
• pp.175-179
• /
• 1996

Viral surface proteins are known to play an essential role in attachment of the virus particle to the host cell membrane. In case of the hepatitis B virus (HBV) several reports have described potential receptors on the target cell side, but no definite receptor protein has been isolated yet. As for the viral side, it has been suggested that the preS region of the envelope protein, especially the preS1 region, is involved in binding of HBV to the host cell. In this study, preS1 region was recombinantly expressed in the form of a maltose binding protein (MBP) fusion protein and used to identify and visualize the expression of putative HBV receptor(s) on the host cell. Using laser scanned confocal microscopy and by FACS analysis, MBP-preS1 proteins were shown to bind to the human hepatoma cell line HepG2 in a receptor-ligand specific manner. The binding kinetic of MBP-preS1 to its cellular receptor was shown to be temperature and time dependent. In cells permeabilized with Triton X-100 and treated with the fusion protein, a specific staining of the nuclear membrane could be observed. To determine the precise location of the receptor binding site within the preS1 region, several short overlapping peptides from this region were synthesized and used in a competition assay. In this way the receptor binding epitope in preS1 was revealed to be amino acid residues 27 to 51, which is in agreement with previous reports. These results confirm the significance of the preS1 region in virus attachment in general, and suggest an internalization pathway mediated by direct attachment of the viral particle to the target cell membrane.

• IMMUNE NETWORK
• /
• v.1 no.1
• /
• pp.77-86
• /
• 2001

Background: Hepatitis C virus(HCV), a family of Flaviviridae, has a host cell-derived envelope containing a positive-stranded RNA genome, and has been known as the maj or etiological agent for chronic hepatitis, hepatic cirrhosis, and hepatocellular carcinoma. There remains a need to dissect a molecular mechanism of pathogenesis for the development of therapeutic and effective preventive measure for HCV. Identification of cellular receptor is of central importance not only to understand the viral pathogenesis, but also to exploit strategies for prevention of HCV. This study was aimed at identifying peptide mimotopes inhibiting the binding of E2 protein of HCV to MOLT-4 cell. Methods: In this study, phage peptide library displaying a random peptides consisting of 7 or 12 random peptides was employed in order to pan against E2 protein. Free HCV particles were separated from the immune complex forms by immunoprecipitation using anti-human IgG antibody, and used for HCV-capture ELISA. To identify the peptides inhibiting E2-binding to MOLT-4 cells, E2 protein was subj ect to bind to MOLT-4 cells under the competition with phage peptides. Results: Several phage peptides were selected for their specific binding to E2 protein, which showed the conserved sequence of SHFWRAP from 3 different peptide sequences. They were also able to recognize the HCV particles in the sera of HCV patients captured by monoclonal antibody against E2 protein. Two of them, showing peptide sequence of HLGPWMSHWFQR and WAPPLERSSLFY respectively, were revealed to inhibit the binding of E2 protein to MOLT-4 cell efficiently in dose dependent mode. However, few membrane-associated receptor candidates were seen using Fasta3 programe for homology search with these peptides. Conclusion: Phage peptides containing HLGPWMSHWFQR and WAPPLERSSLFY respectively, showed the inhibition of E2-binding to MOLT-4 cells. However, they did not reveal any homologues to cellular receptors from GenBank database. In further study, cellular receptor could be identified through the screening of cDNA library from MOLT-4 or hepatocytes using antibodies against these peptide mimotopes.

• Bulletin of the Korean Chemical Society
• /
• v.19 no.10
• /
• pp.1119-1121
• /
• 1998

• Journal of Veterinary Clinics
• /
• v.21 no.3
• /
• pp.253-258
• /
• 2004

DNA double-strand break (DSB) is a serious treat for the cells including mutations, chromosome rearrangements, and even cell death if not repaired or misrepaired. Ku heterodimer regulatory DNA binding subunits (Ku70/Ku80) bound to double strand DNA breaks are able to interact with 470-kDa DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and the interaction is essential for DNA-dependent protein kinase (DNA-PK) activity. The Ku80 mutants were designed to bind Ku70 but not DNA end binding activity and the peptides were treated in breast cancer cells for co-therapy strategy to see whether the targeted inhibition of DNA-dependent protein kinase (DNA-PK) activity sensitized breast cancer cells to ionizing irradiation or chemotherapy drug to develop a treatment of breast tumors by targeting proteins involved in damage-signaling pathway and/or DNA repair. We designed domains of Ku80 mutants, 26 residues of amino acids (HN-26) as a control peptide or 38 (HNI-38) residues of amino acids which contain domains of the membrane-translocation hydrophobic signal sequence and the nuclear localization sequence, but HNI-38 has additional twelve residues of peptide inhibitor region. We observed that the synthesized peptide (HNI-38) prevented DNA-PKcs from binding to Ku70/Ku80, resulting in inactivation of DNA-PK complex activity in breast cancer cells (MDA-465 and MDA-468). Consequently, the peptide treated cells exhibited poor to no DNA repair, and became highly sensitive to irradiation or chemotherapy drugs. The growth of breast cancer cells was also inhibited. These results demonstrate the possibility of synthetic peptide to apply breast cancer therapy to induce apoptosis of cancer cells.

• Parasites, Hosts and Diseases
• /
• v.47 no.1
• /
• pp.31-36
• /
• 2009

Cockroaches have been recognized as a major cause of asthma. Bla g 4 is one of the most important German cockroach allergens. The aim of this study is to investigate IgE reactivity to the recombinant Bla g 4 (rBla g 4) in the sera of allergic patients and identify linear IgE binding epitope. For protein expression, full-length Bla g 4 (EF202172) was divided into 5 overlapping peptide fragments (E1: aa 1-100, E2: aa 34-77, E3: aa 74-117, E4: aa 114-156, and E5: aa 153-182). The full-length and 5 peptide fragments of Bla g 4 was generated by PCR and over-expressed in E. coli BL21 (DE3). The IgE binding reactivities of the full-length and peptide fragments were measured by ELISA using 32 serum samples of cockroach allergy. The sera of 8 patients (25%) reacted with rBla g 4. Four sera (100%) showed IgE-binding reactivity to full-length and peptide fragment 4, and 2 sera (50%) reacted with peptide fragment 2. One (20%) serum reacted with peptide fragment 3. The results of ELISA using overlapping recombinant fragments indicated that the epitope region was located at amino acid sequences 34-73 and 78-113, and major IgE epitope of Bla g 4 was located at amino acid sequences 118-152 of C-terminal. B-cell epitope analysis of German cockroach allergen Bla g 4 could contribute to the strategic development of more specific and potentially efficacious immunotherapy.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2001.11a
• /
• pp.97-101
• /
• 2001

The fusion between viral envelope and target cell membrane is a central step of viral infection, and the fusion proteins located at viral envelope mediate such process. Gp41 of HIV is one of the fusion proteins whose structure and mechanism of membrane fusion had been extensively studied. Functionally important motives of gp41 are the N-terminus fusion peptide, the coiled-coil and the membrane proximal C-peptide regions. The role of these regions during the fusion process had been thoroughly examined. Specially, insertion of the fusion peptide into membrane and conformational change of the coiled-coil and C-peptide regions are assumed to be critical for the fusion mechanism. In addition, the coiled-coil region has been shown to interact with membrane, and the C-peptide region regulates the interaction in a dose dependent manner. Furthermore, fusion defective mutations of the coiled-coil region dramatically changed its binding affinity to membrane. These results suggested that the membrane binding property of the coiled-coil region is important for the fusion activity of gp41, and such property could be modulated by the interaction with the C-peptide region.