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Hai Bo Liu,Kyong Pyo Koh,이준희,김정선,박성훈 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.2
The quorum sensing (QS) mechanism of Pseudomonas aeruginosa has been studied extensively due to its involvement in cystic fibrosis, a deadly disease that is responsible for the death of more than a thousand people annually. In order to develop biochemical assay method for screening QS inhibitor, we have studied the production and characterization of recombinant LasR protein, which is a transcriptional activator for the QS mechanism in P.aeruginosa. In recombinant Escherichia coli BL21, LasR was produced as functionally-active proteins when the cells were cultivated in the presence of a proper signaling molecule (acyl homoserine lactone, AHL) only. Some soluble LasR proteins could be obtained from the cells which were grown in AHL-deficient medium, but they did not show binding affinity to the promoter sequence OP1 (lasB elastase promoter). Furthermore, the active LasR, presumably produced as LasR-AHL complex, was not dissociated into its components (LasR and AHLs)in vitro. The current results indicate that the production of pure and active LasR devoid of AHL is very difficult. It can be concluded that the development of biochemical assay method for screening AHL competitive inhibitors which requires pure and active LasR proteins might not be possible unless the structure of LasR and/or its folding processes is modified
Hai Bo Liu,고경표,김정선,서영완,박성훈 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.4
A mixture of three compounds (betonicine, floridoside, and isethionic acid) purified from the red alga Ahnfeltiopsis flabelliformis, was reported to have an inhibition activity on bacterial quorum sensing mechanism mediated by N-octanoyl-DL-homoserine lactone (OHL) and the TraR transcriptional activator protein. We subsequently conducted a more detailed investigation of the three compounds using chemically synthesized (betonicine and floridoside) or commercially available (isethionic acid) compounds, individually or in various combinations. When tested alone, none of the three compounds inhibited OHL, but a mixture of floridoside and isethionic acid exhibited a dose-dependent inhibitory effect on the function of OHL. In contrast, betonicine or its isomer exhibited a dose-dependent stimulatory effect, similar to OHL, at concentrations between 10-³and 10-6M. These three compounds will be useful for elucidating the interaction between OHL and TraR, and for developing novel bacterial quorum-sensing inhibitors.
Molecular Cloning and Bioinformatic Analysis of SPATA4 Gene
Liu, Shang-Feng,Ai, Chao,Ge, Zhong-Qi,Liu, Hai-Luo,Liu, Bo-Wen,He, Shan,Wang, Zhao Korean Society for Biochemistry and Molecular Biol 2005 Journal of biochemistry and molecular biology Vol.38 No.6
Full-length cDNA sequences of four novel SPATA4 genes in chimpanzee, cow, chicken and ascidian were identified by bioinformatic analysis using mouse or human SPATA4 cDNA fragment as electronic probe. All these genes have 6 exons and have similar protein molecular weight and do not localize in sex chromosome. The mouse SPATA4 sequence is identified as significantly changed in cryptorchidism, which shares no significant homology with any known protein in swissprot databases except for the homologous genes in various vertebrates. Our searching results showed that all SPATA4 proteins have a putative conserved domain DUF1042. The percentages of putative SPATA4 protein sequence identity ranging from 30% to 99%. The high similarity was also found in 1 kb promoter regions of human, mouse and rat SPATA4 gene. The similarities of the sequences upstream of SPATA4 promoter also have a high proportion. The results of searching SymAtlas (http://symatlas.gnf.org/SymAtlas/) showed that human SPATA4 has a high expression in testis, especially in testis interstitial, leydig cell, seminiferous tubule and germ cell. Mouse SPATA4 was observed exclusively in adult mouse testis and almost no signal was detected in other tissues. The pI values of the protein are negative, ranging from 9.44 to 10.15. The subcellular location of the protein is usually in the nucleus. And the signal peptide possibilities for SPATA4 are always zero. Using the SNPs data in NCBI, we found 33 SNPs in human SPATA4 gene genomic DNA region, with the distribution of 29 SNPs in the introns. CpG island searching gives the data about CpG island, which shows that the regions of the CpG island have a high similarity with each other, though the length of the CpG island is different from each other.This research is a fundamental work in the fields of the bioinformational analysis, and also put forward a new way for the bioinformatic analysis of other genes.
Liu, Hai-Bo,Yu, Daun,Shin, Sung Chul,Park, Hyoung-Ryun,Park, Jong Keun,Bark, Ki-Min Wiley (Blackwell Publishing) 2009 Photochemistry and photobiology Vol.85 No.4
<P>The characteristic fluorescence properties of quercetin-3-O-rhamnoside (QCRM) and quercetin-3-O-rutinoside (QCRT) were studied in CH3OH-H2O and CH3CN-H2O mixed solvents. Although QCRM and QCRT are known as nonfluorescent molecules, significant fluorescence emissions were discovered at 360 nm in CH3OH and CH3CN when they were promoted to the second excited state. The emission band is broad and structureless and the intensity decreases quickly as the H2O composition in the solvent increases. When the amount of H2O exceeds 60% in both mixed solvents, this emission disappears due to the formation of the distorted excited state. This state will be formed due to the strong intermolecular hydrogen bonding between the polar groups of solute and H2O. As the composition of CH3OH or CH3CN in solvent becomes large, the number of molecules having several intramolecular hydrogen bonding increases. Some of these molecules will be changed to a fluorescent species during the decay process, after excitation. The theoretical calculation further supports these results. The change of the lifetimes, quantum yields, and radiative and nonradiative rate constants of molecules was also examined as a function of solvatochromic parameters for CH3OH-H2O and CH3CN-H2O.</P>
Comprehensive Study on Associations Between Nine SNPs and Glioma Risk
Liu, Hai-Bo,Peng, Yu-Ping,Dou, Chang-Wu,Su, Xiu-Lan,Gao, Nai-Kang,Tian, Fu-Ming,Bai, Jie Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10
Aim: Glioma cancer is the most common type of adult brain tumor. Recent genome-wide association studies (GWAS) have identified various new susceptibility regions and here we conducted an extensive analysis of associations between 12 single nucleotide polymorphisms (SNPs) and glioma risk. Methods: A total of 197 glioma cases and 197 health controls were selected, and 9 SNPs in 8 genes were analyzed using the Sequenom MassARRAY platform and Sequenom Assay Design 3.1 software. Results: We found the MAF among selected controls were consistent with the MAF from the NCBI SNP database. Among 9 SNPs in 8 genes, we identified four significant SNP genotypes associated with the risk of glioma, C/C genotype at rs730437 and T/T genotype at rs1468727 in ERGF were protective against glioma, whereas the T/T genotype at rs1799782 in XRCC1 and C/C genotype at rs861539 in XRCC3 conferred elevated risk. Conclusion: Our comprehensive analysis of nine SNPs in eight genes suggests that the rs730437 and rs1468727 in ERGF, rs1799782 in XRCC1 gene, and rs861539 in XRCC3 gene are associated with glioma risk. These findings indicate that genetic variants of various genes play a complex role in the development of glioma.