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Pham Ngoc Son,Tran Trung Duy,Pham Viet Tuan,Tan-Phuoc Huynh Electronics and Telecommunications Research Instit 2023 ETRI Journal Vol.45 No.1
We propose short packet communication in an underlay cognitive radio network assisted by an intelligent reflecting surface (IRS) composed of multiple reconfigurable reflectors. This scheme, called the IRS protocol, operates in only one time slot (TS) using the IRS. The IRS adjusts its phases to give zero received cumulative phase at the secondary destination, thereby enhancing the end-to-end signal-to-noise ratio. The transmitting power of the secondary source is optimized to simultaneously satisfy the multi-interference constraints, hardware limitations, and performance improvement. Simulation and analysis results of the average block error rates (BLERs) show that the performance can be enhanced by installing more reconfigurable reflectors, increasing the blocklength, lowering the number of required primary receivers, or sending fewer information bits. Moreover, the proposed IRS protocol always outperforms underlay relaying protocols using two TSs for data transmission, and achieves the best average BLER at identical transmission distances between the secondary source and secondary destination. The theoretical analyses are confirmed by Monte Carlo simulations.
Structural insights into the binding of lauric acid to CYP107L2 from <i>Streptomyces avermitilis</i>
Han, Songhee,Pham, Tan-Viet,Kim, Joo-Hwan,Lim, Young-Ran,Park, Hyoung-Goo,Jeong, Dabin,Yun, Chul-Ho,Chun, Young-Jin,Kang, Lin-Woo,Kim, Donghak Elsevier 2017 Biochemical and biophysical research communication Vol.482 No.4
<P><B>Abstract</B></P> <P> <I>Streptomyces avermitilis</I> is an actinobacterium known to produce clinically useful macrolides including avermectins. CYP107L2 from <I>S. avermitilis</I> shares a high sequence similarity with the PikC (CYP107L1) from <I>S. venezuelae</I>. To elucidate the structural features of CYP107L2, we conducted biochemical and structural characterization of CYP107L2 from <I>S. avermitilis</I>. The CYP107L2 gene was cloned, and its recombinant protein was expressed and purified. The CYP107L2 showed a low-spin state of heme, and the reduced form yielded the CO difference spectra with a maximal absorption at 449 nm. Binding of pikromycin and lauric acid yielded the typical type I spectra with <I>K</I> <SUB>d</SUB> values of 4.8 ± 0.3 and 111 ± 9 <I>μ</I>M, respectively. However, no metabolic product was observed in the enzyme reaction. X-ray crystal structures of the ligand-free CYP107L2 and its complex with lauric acid were determined at the resolution of 2.6 and 2.5 Å, respectively. CYP107L2 showed a well-conserved CYP structure with a wide-open substrate-binding cavity. The lauric acid is bound mainly via hydrophobic interactions with the carboxylate group of lauric acid coordinated to the heme of P450. Glu-40 and Leu-382 residues in the CYP107L2 complex with lauric acid showed significant conformational changes to provide plentiful room for the lauric acid in the substrate-binding site.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CYP107L2 from <I>S. avermitilis</I> shares a high sequence similarity with the PikC. </LI> <LI> Purified CYP107L2 yielded a typical type I binding spectra to pikromycin and lauric acid. </LI> <LI> Crystal structure of CYP107L2 complex with lauric acid was determined at 2.5 Å resolution. </LI> <LI> Laurate is bound mainly via hydrophobic interactions in the substrate binding cavity of CYP107L2. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Songhee HAN,Tan-Viet Pham,Joo-Hwan Kim,임영란,Hyoung-Goo Park,Gun-Su Cha,Chul-Ho Yun,Young-Jin Chun,강린우,김동학 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.3
CYP107W1 from Streptomyces avermitilis is a cytochrome P450 enzyme involved in the biosynthesis of macrolide oligomycin A. A previous study reported that CYP107W1 regioselectively hydroxylated C12 of oligomycin C to produce oligomycin A, and the crystal structure of ligand free CYP107W1 was determined. Here, we analyzed the structural properties of the CYP107W1-oligomycin A complex and characterized the functional role of the Trp178 residue in CYP107W1. The crystal structure of the CYP107W1 complex with oligomycin A was determined at a resolution of 2.6 Å. Oligomycin A is bound in the substrate access channel on the upper side of the prosthetic heme mainly by hydrophobic interactions. In particular, the Trp178 residue in the active site intercalates into the large macrolide ring, thereby guiding the substrate into the correct binding orientation for a productive P450 reaction. A Trp178 to Gly mutation resulted in the distortion of binding titration spectra with oligomycin A, whereas binding spectra with azoles were not affected. The Gly178 mutant’s catalytic turnover number for the 12-hydroxylation reaction of oligomycin C was highly reduced. These results indicate that Trp178, located in the open pocket of the active site, may be a critical residue for the productive binding conformation of large macrolide substrates.
Han, Songhee,Pham, Tan-Viet,Kim, Joo-Hwan,Lim, Young-Ran,Park, Hyoung-Goo,Cha, Gun-Su,Yun, Chul-Ho,Chun, Young-Jin,Kang, Lin-Woo,Kim, Donghak Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.3
CYP107W1 from Streptomyces avermitilis is a cytochrome P450 enzyme involved in the biosynthesis of macrolide oligomycin A. A previous study reported that CYP107W1 regioselectively hydroxylated C12 of oligomycin C to produce oligomycin A, and the crystal structure of ligand free CYP107W1 was determined. Here, we analyzed the structural properties of the CYP107W1-oligomycin A complex and characterized the functional role of the Trp178 residue in CYP107W1. The crystal structure of the CYP107W1 complex with oligomycin A was determined at a resolution of $2.6{\AA}$. Oligomycin A is bound in the substrate access channel on the upper side of the prosthetic heme mainly by hydrophobic interactions. In particular, the Trp178 residue in the active site intercalates into the large macrolide ring, thereby guiding the substrate into the correct binding orientation for a productive P450 reaction. A Trp178 to Gly mutation resulted in the distortion of binding titration spectra with oligomycin A, whereas binding spectra with azoles were not affected. The Gly178 mutant's catalytic turnover number for the 12-hydroxylation reaction of oligomycin C was highly reduced. These results indicate that Trp178, located in the open pocket of the active site, may be a critical residue for the productive binding conformation of large macrolide substrates.
Chien Vien Chinh,Viet Phu Quoc,Loc Huynh Tan,Duoc Nguyen Van,Thai Pham Quang,Be Le Van 한국역학회 2021 Epidemiology and Health Vol.43 No.-
OBJECTIVES: An A/H5N1 vaccine (IVACFLU-A/H5N1) was accepted for use in Vietnam; however, antibody persistence after vaccination has not been well characterized. We examined post-vaccination antibody persistence and related risk factors in individuals enrolled in the phase II IVACFLU-A/ H5N1 vaccine trial in Ninh Hoa, Vietnam, who received a 15-μg dose (2 injections 21 days apart). METHODS: We used a longitudinal study design to follow 86 participants, without a control group. The participants tested as anti-A/H5N1 immunoglobulin G seronegative at baseline and received both doses of the vaccine. Blood was drawn at 30 months and 36 months after the complete vaccination to assess antibody status. Antibody persistence status was compared by demographic characteristics and exposure risk factors using univariate logistic regression. RESULTS: In total, 84.9% and 52.3% of the population showed persistence of at least 1/10 of the A/H5N1 antibodies at 30 months and 36 months after IVACFLU-A/H5N1 vaccination, respectively. The odds of antibody persistence were higher in older people, but lower in people who had experienced flu-like symptoms in the past 18 months or between 2 visits. We recorded no differences between A/H5N1 antibody persistence and exposure risk factors, including having a poultry farm, coming into contact with poultry, and slaughtering and processing poultry. CONCLUSIONS: This study demonstrated noteworthy antibody persistence, indicated by the seroconversion rate and geometric mean titer at 30 months and 36 months after the IVACFLU-A/H5N1 vaccine. Further studies should investigate older people and those who experienced flu-like symptoms to determine a suitable time for a booster shot.
Sampath Natarajan,강린우,김진광,Tae-Kyun Jung,Thanh Thi Ngoc Doan,Ho-Phuong-Thuy Ngo,홍명기,Seunghwan Kim,Viet Pham Tan,Seok Joon Ahn,이상희,한예선,안예진 한국분자세포생물학회 2012 Molecules and cells Vol.33 No.1
Xanthomonas oryzae pv. oryzae (Xoo) is a plant bacterial pathogen that causes bacterial blight (BB) disease, resulting in serious production losses of rice. The crystal structure of malonyl CoA-acyl carrier protein transacylase (XoMCAT), encoded by the gene fabD (Xoo0880) from Xoo, was determined at 2.3 Å resolution in complex with N-cyclohexyl-2-aminoethansulfonic acid. Malonyl CoA-acyl carrier protein transacylase transfers malonyl group from malonyl CoA to acyl carrier protein (ACP). The transacylation step is essential in fatty acid synthesis. Based on the rationale, XoMCAT has been considered as a target for antibacterial agents against BB. Protein-protein interaction between XoMCAT and ACP was also extensively investigated using computational docking, and the proposed model revealed that ACP bound to the cleft between two XoMCAT subdomains.
( Seung Hwan Kim ),( Thi Dieu Hanh Nguyen ),( Joo Hee Lee ),( Myoung Ki Hong ),( Tan Viet Pham ),( Yeh Jin Ahn ),( Byoung Moo Lee ),( Ye Sun Han ),( Dong Eun Kim ),( Jeong Gu Kim ),( Lin Woo Kang ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.1
Xo2276 is a putative transcription activator-like effector (TALE) in Xanthomonas oryzae pv. oryzae (Xoo). Xo2276 was expressed with a TAP-tag at the C-terminus in Xoo cells to enable quantitative analysis of protein expression and secretion. Nearly all TAP-tagged Xo2276 existed in an insoluble form; addition of rice leaf extracts from a Xoosusceptible rice cultivar, Milyang23, significantly stimulated secretion of TAP-tagged Xo2276 into the medium. In a T3SS-defective Xoo mutant strain, secretion of TAPtagged Xo2276 was blocked. Xo2276 is a Xoo ortholog of Xanthomonas campestris pv. vesicatoria (Xcv) AvrBs3 and contains a conserved DNA-binding domain (DBD), which includes 19.5 tandem repeats of 34 amino acids. Xo2276- DBD was expressed in E. coli and purified. Direct in vitro recognition of Xo2276-DBD on a putative target DNA sequence was confirmed using an electrophoretic mobility shift assay. This is the first study measuring the homologous expression and secretion of Xo2276 in vitro using rice leaf extract and its direct in vitro binding to the specific target DNA sequence.