• BMB Reports
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• 제51권3호
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• pp.126-133
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• 2018

Hippo signaling plays critical roles in regulation of tissue homeostasis, organ size, and tumorigenesis by inhibiting YES-associated protein (YAP) and PDZ-binding protein TAZ through MST1/2 and LATS1/2 pathway. It is also engaged in cross-talk with various other signaling pathways, including WNT, BMPs, Notch, GPCRs, and Hedgehog to further modulate activities of YAP/TAZ. Because YAP and TAZ are transcriptional coactivators that lack DNA-binding activity, both proteins must interact with DNA-binding transcription factors to regulate target gene's expression. To activate target genes involved in cell proliferation, TEAD family members are major DNA-binding partners of YAP/TAZ. Accordingly, YAP/TAZ were originally classified as oncogenes. However, YAP might also play tumor-suppressing role. For example, YAP can bind to DNA-binding tumor suppressors including RUNXs and p73. Thus, YAP might act either as an oncogene or tumor suppressor depending on its binding partners. Here, we summarize roles of YAP depending on its DNA-binding partners and discuss context-dependent functions of YAP/TAZ.

• Biomolecules & Therapeutics
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• 제4권2호
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• pp.196-201
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• 1996

The N-methyl-D-aspartate (NMDA) receptor-ion channel complex is activated by the simultaneous presence of L-glutamate and glycine, allowing the binding of MK-801 to the phencyclidine (PCP) site of the receptor. The $[^3H]$MK-801 binding assay system was established for determination of pharmacological functions of test compounds acting at the glycine site of the receptor. The binding in the presence of 0.1 $\mu$M L-glutamate was increased by an agonist (glycine) in a dose-dependent fashion, while decreased by either partial agonist (R-(+)-HA-966) or antagonist (5,7-dichlorokynurenic acid: 5,7-DCKA). To distinguish partial agonism from antagonism, various concentrations of 7-chlorokynurenic acid (7-CKA) were added in the assay to eliminate the interference of the endogenous glycine present in the membrane preparations. The bindings in the presence of L-glutamate (0.1$\muM$) and 7-CKA (1, 5, or 10$\muM$) were increased by R-(+)-HA-966. Being a weak partial agonist, the extent of potentiation was much less than that by the agonist. These binding profiles were clearly distinguishable from those by the antagonist, 5,7-DCKA, which exhibited no intrinsic activity. The binding assays established in the present study are a useful system to classify ligands acting at the glycine site of the NMDA receptor by their pharmacological functions.

• 한국미생물·생명공학회지
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• 제51권3호
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• pp.243-249
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• 2023

We recently found that the insect-derived antimicrobial peptide CopA3 (LLCIALRKK) directly binds to and inhibits the proteolytic activation of caspases, which play essential roles in apoptotic processes. However, the mechanism of CopA3 binding to caspases remained unknown. Here, using recombinant GST-caspase-3 and -6 proteins, we investigated the mechanism by which CopA3 binds to caspases. We showed that replacement of cysteine in CopA3 with alanine caused a marked loss in its binding activity towards caspase-3 and -6. Exposure to DTT, a reducing agent, also diminished their interaction, suggesting that this cysteine plays an essential role in caspase binding. Experiments using deletion mutants of CopA3 showed that the last N-terminal leucine residue of CopA3 peptide is required for binding of CopA3 to caspases, and that C-terminal lysine and arginine residues also contribute to their interaction. These conclusions are supported by binding experiments employing direct addition of CopA3 deletion mutants to human colonocyte (HT29) extracts containing endogenous caspase-3 and -6 proteins. In summary, binding of CopA3 to caspases is dependent on a cysteine in the intermediate region of the CopA3 peptide and a leucine in the N-terminal region, but that both an arginine and two adjacent lysines in the C-terminal region of CopA3 also contribute. Collectively, these results provide insight into the interaction mechanism and the high selectivity of CopA3 for caspases.

• BMB Reports
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• 제42권7호
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• pp.411-417
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• 2009

Transcriptional activation domain (TAD) in virion protein 16 (VP16) of herpes simplex virus does not have any globular structure, yet exhibits a potent transcriptional activity. In order to probe the structural basis for the transcriptional activity of VP16 TAD, we have used NMR spectroscopy to investigate its detailed structural features. Results show that an unbound VP16 TAD is not merely "unstructured" but contains four short motifs (residues 424-433, 442-446, 465-467 and 472-479) with transient structural order. Pre-structured motifs in other intrinsically unfolded proteins (IUPs) were shown to be critically involved in target protein binding. The 472-479 motif was previously shown to bind to $hTAF_{II}31$, whereas the $hTAF_{II}31$-binding ability of other motifs found in this study has not been addressed. The VP16 TAD represents another IUP whose pre-structured motifs mediate promiscuous binding to various target proteins.

• BMB Reports
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• 제49권8호
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• pp.431-436
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• 2016

Human papillomavirus (HPV) is the major cause of cervical cancer, a deadly threat to millions of females. The early oncogene product (E7) of the high-risk HPV16 is the primary agent associated with HPV-related cervical cancers. In order to understand how E7 contributes to the transforming activity, we investigated the structural features of the flexible N-terminal region (46 residues) of E7 by carrying out N-15 heteronuclear NMR experiments and replica exchange molecular dynamics simulations. Several NMR parameters as well as simulation ensemble structures indicate that this intrinsically disordered region of E7 contains two transient (10-20% populated) helical pre-structured motifs that overlap with important target binding moieties such as an E2F-mimic motif and a pRb-binding LXCXE segment. Presence of such target-binding motifs in HPV16 E7 provides a reasonable explanation for its promiscuous target-binding behavior associated with its transforming activity.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2003년도 Annual Meeting of KSAP : International Symposium on Pharmaceutical and Biomedical Sciences on Obesity
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• pp.114-114
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• 2003

Ginseng is a medicinal herb widely used in Asian countries, and its pharmacological effects has been demonstrated in various systems such as cardiovascular, central nervous, and endocrine systems. Its effects are mainly attributed to the ginsenosides. We hypothesize that a component of Panax ginseng, ginsenoside-Rbl, acts by binding to estrogen receptor. We have investigated the estrogenic activity of ginsenoside-Rbl in a transient transfection system using estrogen receptors ${\alpha}$ or ${\beta}$ with estrogen -responsive luciferase plasmids in COS monkey kidney cells. Ginsenoside-Rbl activated both estrogen receptors ${\alpha}$ and ${\beta}$ in a dose-dependent manner (0.5 -100 M ). Activation was inhibited by the specific estrogen receptor antagonist ICI 182,780, indicating that the estrogenic effect of ginsenoside-Rbl is estrogen receptor dependent. Next, we evaluated the ability of ginsenoside-Rbl to induce estrogen-responsive progesterone receptor gene by semi-quantitative RT-PCR assays. MCF-7 cells treated with l7${\beta}$-estradiol or ginsenoside- Rb1 exhibited an increased expression of progesterone receptor mRNA. However, ginsenoside-Rbl failed to displace the specific binding of ［3H］17${\beta}$-estradiol to estrogen receptor in MCF-7 cells as examined by whole cell ligand binding assays, suggesting that there is no direct interaction of ginsenoside-Rbl with estrogen receptor. Our results indicate that estrogen-like activity of ginsenoside-Rbl is independent of direct estrogen receptor association.

• 대한화학회지
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• 제62권2호
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• pp.106-112
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• 2018

Ice-binding proteins have an affinity for ice. They create a gap between the melting and freezing points by inhibiting the growth of ice, known as thermal hysteresis (TH). Interestingly, moderately active LeIBP and hyperactive FfIBP are almost identical in primary and tertiary structures, but differ in TH activity. The TH of FfIBP is tenfold higher than that of LeIBP, due to a subtle difference in their ice-binding motifs. To further evaluate the difference in TH, the interactions were investigated by ice-etching and molecular docking. Ice-etching showed that FfIBP binds to the primary and secondary prism, pyramidal, and basal planes; previously, LeIBP was found to bind to the basal and primary prism planes. Docking analysis using shape complementarity (Sc) showed that the hyperactive FfIBP had higher Sc values for all four ice planes than LeIBP, which is comparable with TH. Docking can be used to describe the hyperactivity of IBPs.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.947-955
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• 2011

The complexes [Pd(bpy)(Hex-dtc)]$NO_3$ and [Pt(bpy)(Hex-dtc)]$NO_3$ (bpy is 2,2'-bipyridine and Hex-dtc is hexyldithiocarbamato ligands) were synthesized and characterized by elemental analysis and spectroscopic studies. The cytotoxicity assay of the complexes has been performed on chronic myelogenous leukemia cell line, K562, at micromolar concentration. Both complexes showed cytotoxic activity far better than that of cisplatin under the same experimental conditions. The binding parameters of the complexes with calf thymus DNA (CT-DNA) was investigated using UV-visible and fluorescence techniques. They show the ability of cooperatively intercalating in CT-DNA. Gel filtration studies demonstrated that platinum complex could cleave the DNA. In the interaction studies between the Pd(II) and Pt(II) complexes with CT-DNA, several binding and thermodynamic parameters have been determined, which may provide deeper insights into the mechanism of action of these types of complexes with nucleic acids.

• IMMUNE NETWORK
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• 제16권4호
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• pp.249-255
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• 2016

Exogenous nucleic acids induce an innate immune response in mammalian host cells through activation of the retinoic acid-inducible gene I (RIG-I). We evaluated RIG-I protein for RNA binding and ATPase stimulation with RNA ligands to investigate the correlation with the extent of immune response through RIG-I activation in cells. RIG-I protein favored blunt-ended, double-stranded RNA (dsRNA) ligands over sticky-ended dsRNA. Moreover, the presence of the 5'-triphosphate (5'-ppp) moiety in dsRNA further enhanced binding affinity to RIG-I. Two structural motifs in RNA, blunt ends in dsRNA and 5'-ppp, stimulated the ATP hydrolysis activity of RIG-I. These structural motifs also strongly induced IFN expression as an innate immune response in cells. Therefore, we suggest that IFN induction through RIG-I activation is mainly determined by structural motifs in dsRNA that increase its affinity for RIG-I protein and stimulate ATPase activity in RIG-I.

• 생명과학회지
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• 제5권4호
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• pp.162-169
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• 1995

The glpD genes encoding gly-3-p dehydrogenase is essential for the aerobic growth of E. coli on glycerol or gly-3-p. The glpE gene, the function of which is unknownm is transcribed divergently with respect to glpD gene. Expression of the adjacent but divergently transcribed glpD the glpE genes is positively regulated by the cAMP-CRP complex. In this study, for a precise investigation of the functional elements in the regulatory region for transcription activation by cAMP-CRP, deletion mutation have been introducted into the regulatory region. The effect of the deletion mutant on transcriptional regulation was tested in vivo by $\beta$-galctosidase activity. Deletion mutants in the regulatory region of glpD demonstrated that the presence of the CRP-binding site resulted in an sixfold increase in promoter activity. And also deletion mutants of glpE gene demonstrated that the presence of the CRP-binding site resulted in an eightfold increase in promoter activity. Insertion of 22 bp oligomer in the deletion mutants has shown that the CRP binding site is need for maximal expression of glpD and glpE genes. glpD and glpE gene, cAMP-CRP complex, deletion mutant, transcriptional regulation.