Aeromonas hydrophila cytosolic 5’-methylthioadenosine/S-adenosylhomocysteine nucleosidase MtaN-2

Jinli Chen,Fei Shang,Lulu Wang,Wei Liu,Yuanyuan Chen,Jing Lan,Liming Jin,Nam-Chul Ha,Chunshan Quan,Yongbin Xu 한국구조생물학회 2018 Biodesign Vol.6 No.3

5’-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) plays a critical role in diverse pathways in bacterial cells such as biological methylation, polyamine biosynthesis, methionine recycling, and bacterial quorum sensing. It has been known that MtaN catalyzes the hydrolysis of N-ribosidic bond of adenosine-based substrates such as S-adenosyl-L-homocysteine (SAH), S-methyl-5’-thioadenosine (MTA) and 5’-deoxyadenosine (5’-DOA). In Aeromonas hydrophila, there are two MtnN subfamily proteins: MtaN-1, a periplasmic protein with an N-terminal signal peptide; and MtaN-2, a cytosolic protein. In this study, MtaN-2 from A. hydrophila was successfully expressed and purified using Ni-NTA affinity, Q anion-exchange, and gel-filtration chromatography. We first crystallized apo MtaN-2 but it diffracted to a low resolution of 5.1 Å. New crystals suitable for diffraction were obtained by adding 2 mM adenosine, a substrate analog of MtaN-2 during purification process and the crystals diffracted to the resolution of 2.0 Å. The crystals belong to the trigonal space group P31 or P32, with unit-cell parameters of a = b = 74.94 Å and c = 185.21 Å. The asymmetric unit contains four complexes of MtaN-2 with hydrolysis products of adenosine.

Crystal structure of <i>E. coli</i> ZinT with one zinc-binding mode and complexed with citrate

Chen, Jinli,Wang, Lulu,Shang, Fei,Dong, Yuesheng,Ha, Nam-Chul,Nam, Ki Hyun,Quan, Chunshan,Xu, Yongbin Elsevier 2018 Biochemical and biophysical research communication Vol.500 No.2

<P><B>Abstract</B></P> <P>The ZnuABC ATP-binding cassette transporter found in gram-negative bacteria has been implicated in ensuring adequate zinc import into Zn(II)-poor environments. ZinT is an essential component of ZnuABC and contributes to metal transport by transferring metals to ZnuA, which delivers them to ZnuB in periplasmic zinc recruitment. Although several structures of <I>E. coli</I> ZinT have been reported, its zinc-binding sites and oligomeric state have not been clearly identified. Here, we report the crystal structure of <I>E. coli</I> ZinT at 1.76 Å resolution. This structure contains one zinc ion in its calycin-like domain, and this ion is coordinated by three highly conserved histidine residues (His167, His176 and His178). Moreover, three oxygen atoms (O<SUB>1</SUB>, O<SUB>6</SUB> and O<SUB>7</SUB>) from the citrate molecule interact with zinc, giving the zinc ion stable octahedral coordination. Our EcZinT structure shows the fewest zinc ions bound of all reported EcZinT structures. Crystallographic packing and size exclusion chromatography suggest that EcZinT prefers to form monomers in solution. Our results provide insights into the molecular function of ZinT.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Crystal structure of <I>E. coli</I> ZinT complexed with citrate in one zinc-binding mode. </LI> <LI> The bound zinc shows octahedral coordination by histidine residues and citrate. </LI> <LI> EcZinT exists as a monomer in solution in the absence and presence of zinc ions. </LI> </UL> </P>

Effects of clearance flow on the characteristics of centrifugal pump under low flow rate

Lulu Zheng,Xiaoping Chen,Hua-Shu Dou,Wei Zhang,ZuChao Zhu,Xueli Cheng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

The Reynolds averaged Navier-Stokes equations and the shear stress transport k-ω turbulence model are employed to simulate the centrifugal pump with or without clearance flows. The simulation results have been compared with the experimental data and good agreement has been achieved. Results show that clearance flow causes a decrease in the characteristics of the centrifugal pump, particularly in pressure fluctuation. The largest deviation of the amplitude of pressure fluctuation between the centrifugal pump with and without clearance flow is 65.34 %. The numerical results also show that the clearance flow causes collision impact with the mainstream flow and forms a multiple vortex structure at the impeller entrance. Clearance flow greatly affects the pressure distribution in the impeller passage, which is opposite to the volute tongue, especially at the suction side of the blade surface. The wave distribution decreases along the direction of the hub to the shroud, which indicating that the influence of clearance flow weakens along this direction.

Investigation on characteristics of pressure fluctuation in a centrifugal pump with clearance flow

Lulu Zheng,Xiaoping Chen,Wei Zhang,Zu-chao Zhu,Jinglei Qu,Mengmeng Wang,Xiaojie Ma,Xueli Cheng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.9

Clearance flow has great impact on pressure fluctuation of centrifugal pumps. Numerical calculations are performed to study the pressure fluctuation characteristics of centrifugal pump with wear ring clearance, especially in the regions of interaction between main flow and clearance flow (IMC) and clearance. The accuracy of numerical calculations is illustrated by comparing the experiments of performance and pressure fluctuation. Results show that, in clearance region the pressure fluctuation is still governed by blade passing frequency (f BPF ). Its amplitude of dominate frequency of pressure fluctuation becomes larger as the probe approaches the impeller exit. In IMC region, the pressure fluctuation at impeller outlet is dominated by f BPF . However, the dominate frequency at the entrance of impeller is less than f BPF . In addition, as the flow rate increased, the amplitude of dominate frequency of pressure fluctuation increases at impeller entrance, whereas an inverse trend is observed at wear ring clearance region.

Fertility-preserving treatment outcome in endometrial cancer or atypical hyperplasia patients with polycystic ovary syndrome

Lulu Wang,Xuezhen Luo,Qian Wang,Qiaoying Lv,Pengfei Wu,Wei Liu,Xiaojun Chen 대한부인종양학회 2021 Journal of Gynecologic Oncology Vol.32 No.5

Objective: This study aimed to investigate the impact of polycystic ovary syndrome (PCOS) on fertility-sparing treatment in young patients with atypical endometrial hyperplasia (AEH) or endometrioid endometrial cancer (EEC). Methods: A total of 285 patients with EEC (n=76, FIGO stage IA, without myometrium invasion) or AEH (n=209) who received progestin-based fertility-sparing treatment were evaluated retrospectively. Among the 285 patients, 103 (36.1%), including 70 AEH cases and 33 EEC cases, were diagnosed with PCOS. General characteristics, cumulative 16- and 32-week complete response (CR) rate, pregnancy outcome and recurrence were compared between patients with or without PCOS. Results: The cumulative 16-week CR rate was lower in the PCOS group than in the non- PCOS group (18.4% vs. 33.8%, p=0.006). Patients with PCOS took longer treatment duration to achieve CR (7.0 months vs. 5.4 months, p=0.006) and shorter time to relapse after CR (9.6 months vs. 17.6 months, p=0.040) compared with non-PCOS group. After adjusting for patient age, body mass index, PCOS, homeostasis model assessment-insulin resistance index, and serum testosterone levels, we found that body mass index ≥25 kg/m2 (HR=0.583; 95% CI=0.365–0.932; p=0.024) and PCOS (HR=0.545; 95% CI=0.324–0.917; p=0.022) were significantly correlated with lower 16-week CR rate. Conclusion: PCOS was associated with lower 16-week CR rate, longer treatment duration and shorter recurrence interval in patients with AEH or EEC receiving fertility-preserving treatment.

Cytosolic 5′-Methylthioadenosine/ S-Adenosylhomocysteine Nucleosidase MtaN from Mycobacterium. smegmatis: purification, crystallization and X-ray crystallographic analysis

Lulu Wang,Yuanyuan Chen,Wei Liu,Jing Lan,Fei Shang,Nam-Chul Ha,Yuesheng Dong,Chunshan Quan,Yongbin Xu 한국구조생물학회 2019 Biodesign Vol.7 No.3

Mycobacterium tuberculosis is a dangerous pathogen, and it can cause the most deadly disease tuberculosis (TB). Nonpathogenic Mycobacterium smegmatis is an important model for studying the M. tuberculosis. M. smegmatis 5’-Methylthioadenosine/S-adenosyl-L-homocysteine nucleosidases (MtaNs) catalyze the hydrolysis of adenine from 5’-methylthioadenosine (MTA), MtaNs cleave the glycosidic bond of MTA or S-adenosylhomocysteine (SAH) irreversibly. In this study, MtaN from M. smegmatis (MsMtaN) was successfully expressed and purified using Ni-NTA affinity, Q anionexchange and gel-filtration chromatography. The protein crystal was obtained and diffracted to a resolution of 2.0 Å. The crystal belonged to the orthorhombic space group P1211, with unit-cell parameters of a =57.6, b = 172.6, and c = 183.3 Å. The Matthews coefficient and solvent content were estimated to be 2.32 Å3 Da-1 and 47%, respectively, assuming that the asymmetric unit contained only one recombinant protein molecule. Size-exclusion chromatography suggested that MsMtaN prefer to exist as tetramer in solution.

Characteristics and Health Risks of Particulate Polycyclic Aromatic Hydrocarbons and Nitro-polycyclic Aromatic Hydrocarbons at Urban and Suburban Elementary Schools in Shanghai, China

Lulu Zhang,Takahiro Tokuda,Lu Yang,Quanyu Zhou,Xuan Zhang,Wanli Xing,Qing Wu,Zhijun Zhou,Renjie Chen,Takayuki Kameda,Akira Toriba,Kazuichi Hayakawa,Ning Tang 한국대기환경학회 2019 Asian Journal of Atmospheric Environment (AJAE) Vol.13 No.4

PM2.1 was collected at urban and suburban elementary schools in Shanghai during two sampling periods in cold and warm seasons in 2007. Nine polycyclic aromatic hydrocarbons (PAHs) and ten nitro-polycyclic aromatic hydrocarbons (NPAHs) in PM2.1 were determined. During both seasons, the concentrations of PAHs and NPAHs at urban and suburban schools were not significantly different (p>0.05) and were higher in the cold period than in the warm period. According to the diagnostic ratios, PAHs and NPAHs at both schools were subject to the mixed effects of vehicle emission and coal combustion during both periods. Moreover, the results of the backward trajectory showed that PAHs and NPAHs were more susceptible to external polluted air masses in the cold period. At both urban and suburban schools, the inhalation cancer risk of PAHs and NPAHs in PM2.1 for children during elementary period was dozens of times of the acceptable risk level regulated by the U.S.EPA, highlighting the adverse impact of exposure to PAHs and NPAHs on the healthy development of children.

Metal-Free Photocatalysts C3N3S3 and its Polymers: Solubility in Water and Application in Benzylic Alcohols Oxidation Under Visible Light

Liming Chen,Lulu Zhao,Jie Xu,Jinlin Long,Linxi Hou 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.8

Metal-free photocatalysts trithiocyanuric acid (C3N3S3) and its polymers were one-step synthesized and used for selective aerobic oxidation of benzyl alcohol under visible light. The S–S bridged C3N3S3 polymers showed higher oxidation activity with increasing polymerization time and reached a maximum at 40 h. As a major factor, catalysts' solubility in water at different temperatures (from 298.15K to 368.15 K) was measured at atmospheric pressure. The obtained data were correlated by polynomial empirical equation and modified Apelblat equation, respectively. Experimental results proved that the solubility of C3N3S3 and its polymers increased with increasing temperature. The solubility of C3N3S3 polymers with lower polymerization degree (DP) were better than that of parent C3N3S3 owing to the hydrophilicity caused by a low symmetry and disorder structure, whereas the higher DP could lead to the decrease of polymer solubility and further affect the photocatalytic activity. Thermodynamic properties of the solution system including the enthalpy (△H0S) and heat capacity (c0p) were calculated by the modified Apelblat equation.

Structural insight into the carboxylesterase BioH from <i>Klebsiella pneumoniae</i>

Wang, Lulu,Chen, Yuanyuan,Shang, Fei,Liu, Wei,Lan, Jing,Gao, Peng,Ha, Nam-Chul,Nam, Ki Hyun,Dong, Yuesheng,Quan, Chunshan,Xu, Yongbin Elsevier 2019 Biochemical and biophysical research communication Vol.520 No.3

<P><B>Abstract</B></P> <P>The BioH carboxylesterase which is a typical α/β-hydrolase enzyme involved in biotin synthetic pathway in most bacteria. BioH acts as a gatekeeper and blocks the further elongation of its substrate. In the pathogen <I>Klebsiella pneumoniae</I>, BioH plays a critical role in the biosynthesis of biotin. To better understand the molecular function of BioH, we determined the crystal structure of BioH from <I>K. pneumoniae</I> at 2.26 Å resolution using X-ray crystallography. The structure of KpBioH consists of an α-β-α sandwich domain and a cap domain. B-factor analysis revealed that the α-β-α sandwich domain is a rigid structure, while the loops in the cap domain shows the structural flexibility. The active site of KpBioH contains the catalytic triad (Ser82-Asp207-His235) on the interface of the α-β-α sandwich domain, which is surrounded by the cap domain. Size exclusion chromatography shows that KpBioH prefers the monomeric state in solution, whereas two-fold symmetric dimeric formation of KpBioH was observed in the asymmetric unit, the conserved Cys31-based disulfide bonds can maintain the irreversible dimeric formation of KpBioH. Our study provides important structural insight for understanding the molecular mechanisms of KpBioH and its homologous proteins.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Crystal structure of <I>K. pneumoniae</I>BioH consists of an α-β-αsandwish domain and acapsubdomain. </LI> <LI> The active site of KpBioH contains the catalytic triad (Ser82-Asp207-His235). </LI> <LI> The Arg138, Arg142, Arg155, and Arg159 of KpBioH may play an important role in the binding of the substrates like ACP. </LI> <LI> The Cys31-based disulfide bonds can maintain the irreversible dimeric formation of KpBioH. </LI> </UL> </P>

Impact of NR1I2, adenosine triphosphate-binding cassette transporters genetic polymorphisms on the pharmacokinetics of ginsenoside compound K in healthy Chinese volunteers

Zhou, Luping,Chen, Lulu,Wang, Yaqin,Huang, Jie,Yang, Guoping,Tan, Zhirong,Wang, Yicheng,Liao, Jianwei,Zhou, Gan,Hu, Kai,Li, Zhenyu,Ouyang, Dongsheng The Korean Society of Ginseng 2019 Journal of Ginseng Research Vol.43 No.3

Background: Ginsenoside compound K (CK) is a promising drug candidate for rheumatoid arthritis. This study examined the impact of polymorphisms in NR1I2, adenosine triphosphate-binding cassette (ABC) transporter genes on the pharmacokinetics of CK in healthy Chinese individuals. Methods: Forty-two targeted variants in seven genes were genotyped in 54 participants using Sequenom MassARRAY system to investigate their association with major pharmacokinetic parameters of CK and its metabolite 20(S)-protopanaxadiol (PPD). Subsequently, molecular docking was simulated using the AutoDock Vina program. Results: ABCC4 rs1751034 TT and rs1189437 TT were associated with increased exposure of CK and decreased exposure of 20(S)-PPD, whereas CFTR rs4148688 heterozygous carriers had the lowest maximum concentration ($C_{max}$) of CK. The area under the curve from zero to the time of the last quantifiable concentration ($AUC_{last}$) of CK was decreased in NR1I2 rs1464602 and rs2472682 homozygous carriers, while $C_{max}$ was significantly reduced only in rs2472682. ABCC4 rs1151471 and CFTR rs2283054 influenced the pharmacokinetics of 20(S)-PPD. In addition, several variations in ABCC2, ABCC4, CFTR, and NR1I2 had minor effects on the pharmacokinetics of CK. Quality of the best homology model of multidrug resistance protein 4 (MRP4) was assessed, and the ligand interaction plot showed the mode of interaction of CK with different MRP4 residues. Conlusion: ABCC4 rs1751034 and rs1189437 affected the pharmacokinetics of both CK and 20(S)-PPD. NR1I2 rs1464602 and rs2472682 were only associated with the pharmacokinetics of CK. Thus, these hereditary variances could partly explain the interindividual differences in the pharmacokinetics of CK.