Permeabilized Escherichia coli Whole Cells Containing Co‐Expressed Two Thermophilic Enzymes Facilitate the Synthesis of scyllo‐Inositol from myo‐Inositol

Scyllo‐inositol (SI), a stereoisomer of inositol, is regarded as a promising therapeutic agent for Alzheimer's disease. Here, an in vitro cofactor‐balance biotransformation for the production of SI from myo‐inositol (MI) by thermophilic myo‐inositol 2‐dehydrogenase (IDH) and scyllo‐inositol 2‐dehydrogenase (SIDH) is presented. These two enzymes (i.e., IDH and SIDH from Geobacillus kaustophilus) are co‐expressed in Escherichia coli BL21(DE3), and E. coli cells containing the two enzymes are permeabilized by heat treatment as whole‐cell catalysts to convert MI to SI. After condition optimizations about permeabilized temperature, reaction temperature, and initial MI concentration, about 82 g L^?1 of SI is produced from 250 g L^?1 of MI within 24 h without any cofactor supplementation. This final titer of SI produced is the highest to the authors’ limited knowledge. This study provides a promising method for the large‐scale industrial production of SI.     

重组枯草芽孢杆菌全细胞催化合成2-O-α-D-甘油葡糖苷

2-O-α-D-甘油葡糖苷是一种在食品、化妆品、保健品及医药领域有着重大应用前景的高附加值产品,但国内仍未实现2-O-α-D-甘油葡糖苷的工业化生产,且鲜有关于2-O-α-D-甘油葡糖苷合成的相关报道。文中旨在开发一种利用食品安全级重组枯草芽孢杆菌全细胞催化合成2-O-α-D-甘油葡糖苷的方法,通过构建一株异源表达肠膜明串珠菌蔗糖磷酸化酶 (Sucrose phosphorylase,SPase) 的重组枯草芽孢杆菌Bacillus subtilis 168/pMA5-gtfA,并将其用作全细胞催化剂合成2-O-α-D-甘油葡糖苷,通过优化培养温度、时间及全细胞转化条件,提高其转化合成2-O-α-D-甘油葡糖苷的产量。结果表明,重组枯草芽孢杆菌B. subtilis 168/pMA5-gtfA在30 ℃下培养20 h,菌体裂解物酶活力最大达1.43 U/mL,并且在1 mol/L蔗糖、2.5 mol/L甘油、pH 7.0、菌体OD600为40、30 ℃下全细胞转化反应48 h,共生成2-O-α-D-甘油葡糖苷189.3 g/L,平均转化速率为15.6 mmol/(L·h),蔗糖转化率约为75.1%,是目前报道的利用重组枯草芽孢杆菌催化合成2-O-α-D-甘油葡糖苷的最高产量,这为2-O-α-D-甘油葡糖苷的工业化生产及应用奠定了理论和实验基础。     

Ghrelin Affects Gastric Cancer Progression by Activating AMPK Signaling Pathway

Biochemical Genetics - As the endogenous ligand for the GH secretagogue receptor (GHSR), Ghrelin is aberrant expressed in multiple malignant carcinoma, and involved in regulating a number of...     

Drought stress and plant ecotype drive microbiome recruitment in switchgrass rhizosheath

The rhizosheath, a layer of soil grains that adheres firmly to roots, is beneficial for plant growth and adaptation to drought environments. Switchgrass is a perennial C4 grass which can form contact rhizosheath under drought conditions. In this study, we characterized the microbiomes of four different rhizocompartments of two switchgrass ecotypes (Alamo and Kanlow) grown under drought or well-watered conditions via 16S ribosomal RNA amplicon sequencing. These four rhizocompartments, the bulk soil, rhizosheath soil, rhizoplane, and root endosphere, harbored both distinct and overlapping microbial communities. The root compartments (rhizoplane and root endosphere) displayed low-complexity communities dominated by Proteobacteria and Firmicutes. Compared to bulk soil, Cyanobacteria and Bacteroidetes were selectively enriched, while Proteobacteria and Firmicutes were selectively depleted, in rhizosheath soil. Taxa from Proteobacteria or Firmicutes were specifically selected in Alamo or Kanlow rhizosheath soil. Following drought stress, Citrobacter and Acinetobacter were further enriched in rhizosheath soil, suggesting that rhizosheath microbiome assembly is driven by drought stress. Additionally, the ecotype-specific recruitment of rhizosheath microbiome reveals their differences in drought stress responses. Collectively, these results shed light on rhizosheath microbiome recruitment in switchgrass and lay the foundation for the improvement of drought tolerance in switchgrass by regulating the rhizosheath microbiome.     

Curvature-Dependent Cavity-Nanoparticle Scaffold-Based Clusters with LSPR Enhancement as SERS Substrates

Plasmonics - Tunable local surface plasmon resonance (LSPR) enhancement properties of cavity-nanoparticle scaffold-based clusters were investigated via finite-difference time-domain (FDTD)...     

The protein kinase 2 inhibitor CX-4945 regulates osteoclast and osteoblast differentiation In vitro

Drug repositioning can identify new therapeutic applications for existing drugs, thus mitigating high R&D costs. The Protein kinase 2 (CK2) inhibitor CX-4945 regulates human cancer cell survival and angiogenesis. Here we found that CX-4945 significantly inhibited the RANKL-induced osteoclast differentiation, but enhanced the BMP2-induced osteoblast differentiation in a cell culture model. CX-4945 inhibited the RANKL-induced activation of TRAP and NFATc1 expression accompanied with suppression of Akt phosphorylation, but, in contrast, it enhanced the BMP2-mediated ALP induction and MAPK ERK1/2 phosphorylation. CX-4945 is thus a novel drug candidate for bone-related disorders such as osteoporosis.     

Role of Complement 3 in TNF-α-Induced Mesenchymal Transition of Renal Tubular Epithelial Cells In Vitro

Injured renal tubular epithelial cells (RTECs) have been recently thought to directly contribute to the accumulation of myofibroblasts in renal tubulointerstitial fibrosis through a process of epithelial to mesenchymal transition (EMT). However, the factors inducing RTECs to undergo EMT and the underlying mechanisms need to be further elucidated. This study aimed to determine the EMT-inducing activity of proinflammatory cytokine TNF-α and the role for complement 3 (C3) in this activity in an in vitro model of human RTECs (HK-2 cells). Wild type HK-2 cells were treated with TNF-α, IFN-γ or C3a; C3 siRNA- or control siRNA-carrying HK-2 cells were treated with TNF-α. Changes in the cell morphology and phenotype were assessed by microscopy, RT-PCR, western blotting, and immunostaining. TNF-α effectively induced HK-2 cells to express C3 and to transform into morphologically myofibroblast-like cells that lost E-cadherin (a classical epithelial cell marker) expression but acquired alpha-smooth muscle actin (α-SMA, a classical myofibroblast differentiation marker) expression. C3 siRNA robustly attenuated all the morphologic and phenotypic changes induced by TNF-α but the control siRNA showed no effect. Our preliminary observations suggest that TNF-α may induce EMT in RTECs through inducing C3 expression.