Expression, purification, and characterization of transmembrane protein homogentisate solanesyltransferase.

Homogentisate solanesyltransferase (HST) is a crucial enzyme in the plastoquinone biosynthetic pathway and has recently emerged as a promising target for herbicides. In this study, we successfully expressed and purified a stable and highly pure form of seven times transmembrane protein Chlamydomonas reinhardtii HST (CrHST). The final yield of CrHST protein obtained was 12.2 mg per liter of M9 medium. We evaluated the inhibitory effect on CrHST using Des-Morpholinocarbony Cyclopyrimorate (DMC) and found its IC50 value to be 3.63 ± 0.53 µM, indicating significant inhibitory potential. Additionally, we investigated the substrate affinity of CrHST with two substrates, determining the Km values as 22.76 ± 1.70 µM for FPP and 48.54 ± 3.89 µM for HGA. Through sequence alignment analyses and three-dimensional structure predictions, we identified conserved amino acid residues forming the active cavity in the enzyme. The results from molecular docking and binding energy calculations indicate that DMC has a greater binding affinity with HST compared to HGA. These findings represent substantial progress in understanding CrHST's properties and potential for herbicide development. KEY POINTS: • First high-yield transmembrane CrHST protein via E. coli system • Preliminarily identified active cavity composition via activity testing • Determined substrate and inhibitor modes via molecular docking.

Discovery and Development of 4-Hydroxyphenylpyruvate Dioxygenase as a Novel Crop Fungicide Target.

Plant pathogenic fungi pose a significant threat to crop yields and quality, and the emergence of fungicide resistance has further exacerbated the problem in agriculture. Therefore, there is an urgent need for efficient and environmentally friendly fungicides. In this study, we investigated the antifungal activity of (+)-Usnic acid and its inhibitory effect on crop pathogenic fungal 4-hydroxyphenylpyruvate dioxygenases (HPPDs) and determined the structure of Zymoseptoria tritici HPPD (ZtHPPD)-(+)-Usnic acid complex. Thus, the antifungal target of (+)-Usnic acid and its inhibitory basis toward HPPD were uncovered. Additionally, we discovered a potential lead fungicide possessing a novel scaffold that displayed remarkable antifungal activities. Furthermore, our molecular docking analysis revealed the unique binding mode of this compound with ZtHPPD, explaining its high inhibitory effect. We concluded that HPPD represents a promising target for the control of phytopathogenic fungi, and the new compound serves as a novel starting point for the development of fungicides and dual-purpose pesticides.

Discovery of Subnanomolar Inhibitors of 4-Hydroxyphenylpyruvate Dioxygenase via Structure-Based Rational Design.

High-potency 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors are usually featured by time-dependent inhibition. However, the molecular mechanism underlying time-dependent inhibition by HPPD inhibitors has not been fully elucidated. Here, based on the determination of the HPPD binding mode of natural products, the π-π sandwich stacking interaction was found to be a critical element determining time-dependent inhibition. This result implied that, for the time-dependent inhibitors, strengthening the π-π sandwich stacking interaction might improve their inhibitory efficacy. Consequently, modification with one methyl group on the bicyclic ring of quinazolindione inhibitors was achieved, thereby strengthening the stacking interaction and significantly improving the inhibitory efficacy. Further introduction of bulkier hydrophobic substituents with higher flexibility resulted in a series of HPPD inhibitors with outstanding subnanomolar potency. Exploration of the time-dependent inhibition mechanism and molecular design based on the exploration results are very successful cases of structure-based rational design and provide a guiding reference for future development of HPPD inhibitors.

Ascending aortic dilatation rate after transcatheter aortic valve replacement in patients with bicuspid and tricuspid aortic stenosis: A multidetector computed tomography follow-up study / 世界急诊医学杂志（英文）

BACKGROUND@#Current data is lacking about the progression of ascending aortic dilatation after transcatheter aortic valve replacement (TAVR) in aortic stenosis (AS) patients with bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV). This study aims to assess the ascending aortic dilatation rate (mm/ year) after TAVR in patients with BAV versus TAV using a multidetector computed tomography (MDCT) follow-up and to determine the predictors of ascending aortic dilatation rate.@*METHODS@#Severe AS patients undergoing TAVR from March 2013 to March 2018 at our center with MDCT follow-ups were included. BAV and TAV were identified using baseline MDCT. Baseline and follow-up MDCT images were analyzed, and the diameters of ascending aorta were measured. Study end point is ascending aortic dilatation rate (mm/year). Furthermore, factors predicting ascending aortic dilatation rate were also investigated.@*RESULTS@#Two hundred and eight patients were included, comprised of 86 BAV and 122 TAV patients. Five, 4, 3, 2, and 1-year MDCT follow-ups were achieved in 7, 9, 30, 46, and 116 patients. The ascending aortic diameter was significantly increased after TAVR in both BAV group (43.7±4.4 mm vs. 44.0±4.5 mm; P<0.001) and TAV group (39.1±4.8 mm vs. 39.7±5.1 mm; P<0.001). However, no difference of ascending aortic dilatation rate was found between BAV and TAV group (0.2±0.8 mm/year vs. 0.3±0.8 mm/year, P=0.592). Multivariate linear regression revealed paravalvular leakage (PVL) grade was independently associated with ascending aortic dilatation rate in the whole population and BAV group, but not TAV group. No aortic events occurred during follow-ups.@*CONCLUSION@# Ascending aortic size continues to grow after TAVR in BAV patients, but the dilatation rate is mild and comparable to that of TAV patients. PVL grade is associated with ascending aortic dilatation rate in BAV patients post-TAVR.

First-in-man implantation of the retrievable and repositionable VenusA-Plus valve / 世界急诊医学杂志（英文）

BACKGROUND:No retrievable and repositionable second generation transcatheter aortic valve is available in China. Here, we report the first-in-man implantation of the retrievable and repositionable VenusA-Plus valve. METHODS:A 76-year-old patient with symptomatic severe aortic stenosis and high surgical risk (STS 13.8％) was recommended for transcatheter aortic valve replacement (TAVR) by heart valve team. Type 0 bicuspid aortic valve with asymmetric calcification was identified by dual source computed tomography, and the unfavorable anatomies increased the possibility of malposition and paravalvular leakage during TAVR. Therefore, we used the retrievable and repositionable VenusA-Plus valve for the patient. RESULTS:Transfemoral TAVR was performed under local anesthesia with sedation, and a 26-mm VenusA-Plus valve was successful y implanted. No transvalvular pressure gradient and trace paravalvular leakage were found. CONCLUSION:The successful first-in-man implantation indicates the retrievable and repositionable VenusA-Plus valve is feasible in complicated TAVR cases such as bicuspid aortic valve.

Relationship among the Oxygen Concentration, Reactive Oxygen Species and the Biological Characteristics of Mouse Bone Marrow Hematopoietic Stem Cells / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the effects of oxygen concentration and reactive oxygen species (ROS) on the biological characteristics of hematopoietic stem cells (HSC) and to analyzed the relationship among the oxygen concentration, ROS and the biological characteristics of mouse HSC through simulation of oxygen environment experienced by PB HSC during transplantation.</p><p><b>METHODS</b>The detection of reactive oxygen species (ROS), in vitro amplification, directional differentiation (BFU-E, CFU-GM, CFU-Mix), homing of adhesion molecules (CXCR4, CD44, VLA4, VLA5, P-selectin), migration rate, CFU-S of NOD/SCID mice irradiated with sublethal dose were performed to study the effect of oxgen concentration and reactive oxygen species on the biological characteristics of mouse BM-HSC and the relationship among them.</p><p><b>RESULTS</b>The oxygen concentrations lower than normal oxygen concentration (especially hypoxic oxygen environment) could reduce ROS level and amplify more Lin(-) c-kit(+) Sca-1(+) BM HSC, which was more helpful to the growth of various colonies (BFU-E, CFU-GM, CFU-Mix) and to maintain the migratory ability of HSC, thus promoting CFU-S growth significantly after the transplantation of HSC in NOD/SCID mice irradiated by a sublethal dose. BM HSC exposed to oxygen environments of normal, inconstant oxygen level and strenuously thanging of oxygen concentration could result in higher level of ROS, at the same time, the above-mentioned features and functional indicators were relatively lower.</p><p><b>CONCLUSION</b>The ROS levels of BM HSC in PB HSCT are closely related to the concentrations and stability of oxygen surrounding the cells. High oxygen concentration results in an high level of ROS, which is not helpful to maintain the biological characteristics of BM HSC. Before transplantation and in vitro amplification, the application of antioxidancs and constant oxygen level environments may be beneficial for transplantation of BMMSC.</p>

Effect of different oxygen concentrations on biological properties of bone marrow hematopoietic stem cells of mice / 中国实验血液学杂志

This study purposed to investigate the effects of different oxygen concentrations and reactive oxygen species (ROS) on the biological characteristics of hematopoietic stem cells (HSC) and their possible mechanisms through simulating oxygen environment to which the peripheral blood HSC are subjected in peripheral blood HSCT. The proliferation ability, cell cycle, directed differentiation ability, ROS level and hematopoietic reconstitution ability of Lin(-)c-kit(+)Sca-1(+) BMHSC were detected by using in vitro amplification test, directional differentiation test, cell cycle analysis, ROS assay and transplantation of Lin(-)c-kit(+)Sca-1(+) HSC from sublethally irradiated mice respectively. The results showed that oxygen concentrations lower than normal oxygen concentration, especially in hypoxic oxygen environment, could reduce ROS generation and amplify more primitive CD34(+)AC133(+) HSC and active CD34(+) HSC, and maintain more stem cells in the G(0)/G(1) phase, which is more helpful to the growth of CFU-S and viability of mice. At the same time, BMHSC exposed to normal oxygen level or inconstant and greatly changed oxygen concentrations could produce a high level of ROS, and the above-mentioned features and functional indicators are relatively low. It is concluded that ROS levels of HSC in BMHSCT are closely related with the oxygen concentration surrounding the cells and its stability. Low oxygen concentration and antioxidant intervention are helpful to transplantation of BMHSC.