Enzyme systems involved in glucosinolate metabolism in Companilactobacillus farciminis KB1089

Cruciferous vegetables are rich sources of glucosinolates (GSLs). GSLs are degraded into isothiocyanates, which are potent anticarcinogens, by human gut bacteria. However, the mechanisms and enzymes involved in gut bacteria-mediated GSL metabolism are currently unclear. This study aimed to elucidate the enzymes involved in GSL metabolism in lactic acid bacteria, a type of gut bacteria. Companilactobacillus farciminis KB1089 was selected as a lactic acid bacteria strain model that metabolizes sinigrin, which is a GSL, into allylisothiocyanate. The sinigrin-metabolizing activity of this strain is induced under glucose-absent and sinigrin-present conditions. A quantitative comparative proteomic analysis was conducted and a total of 20 proteins that were specifically expressed in the induced cells were identified. Three candidate proteins, β-glucoside-specific IIB, IIC, IIA phosphotransferase system (PTS) components (CfPttS), 6-phospho-β-glucosidase (CfPbgS) and a hypothetical protein (CfNukS), were suspected to be involved in sinigrin-metabolism and were thus investigated further. We hypothesize a pathway for sinigrin degradation, wherein sinigrin is taken up and phosphorylated by CfPttS, and subsequently, the phosphorylated entity is degraded by CfPbgS. As expression of both pttS and pbgS genes clearly gave Escherichia coli host strain sinigrin converting activity, these genes were suggested to be responsible for sinigrin degradation. Furthermore, heterologous expression analysis using Lactococcus lactis suggested that CfPttS was important for sinigrin degradation and CfPbgS degraded phosphorylated sinigrin

Boron-doped p-BaSi 2/n-Si solar cells formed on textured n-Si(001) with a pyramid structure consisting of {111} facets

BaSi2 films were fabricated on textured Si(0 0 1) substrates that consisted of {1 1 1} facets using molecular beam epitaxy. The light-trapping effect of these films and their performance when incorporated into solar cells were measured. X-ray diffraction and reflectivity measurements showed that the BaSi2 films were grown epitaxially on the textured Si(0 0 1) substrate and confirmed the light-trapping effect. The critical thickness over which BaSi2 relaxes increased from approximately 50 to 100 nm when comparing the BaSi2 films on a flat Si(1 1 1) substrate and the textured substrate, respectively. p-BaSi2/n-Si solar cells were fabricated with varying BaSi2 layer thickness and with hole concentrations in the range between 2.0 × 1018 and 4.6 × 1018 cm−3. These cells exhibited a maximum energy conversion efficiency of 4.62% with an open-circuit voltage of 0.30 V and a short-circuit current density of 27.6 mA/cm2 when the p-BaSi2 layer was 75 nm-thick. These results indicated that the use of BaSi2 films on textured Si(0 0 1) substrates in solar cells shows great promise

Low Surface Potential with Glycoconjugates Determines Insect Cell Adhesion at Room Temperature

Cell-coupled field-effect transistor (FET) biosensors have attracted considerable attention because of their high sensitivity to biomolecules. The use of insect cells (Sf21) as a core sensor element is advantageous due to their stable adhesion to sensors at room temperature. Although visualization of the insect cell-substrate interface leads to logical amplification of signals, the spatiotemporal processes at the interfaces have not yet been elucidated. We quantitatively monitored the adhesion dynamics of Sf21 using interference reflection microscopy (IRM). Specific adhesion signatures with ring-like patches along the cellular periphery were detected. A combination of zeta potential measurements and lectin staining identified specific glycoconjugates with low electrostatic potentials. The ring-like structures were disrupted after cholesterol depletion, suggesting a raft domain along the cell periphery. Our results indicate dynamic and asymmetric cell adhesion is due to low electrostatic repulsion with fluidic sugar rafts. We envision the logical design of cell-sensor interfaces with an electrical model that accounts for actual adhesion interfaces.Matsuzaki T., Terutsuki D., Sato S., et al. Low Surface Potential with Glycoconjugates Determines Insect Cell Adhesion at Room Temperature. Journal of Physical Chemistry Letters 2022 13(40), 9494-9500. DOI: 10.1021/acs.jpclett.2c01673. Copyright © 2022 American Chemical Society

Selective alkylation of T–T mismatched DNA using vinyldiaminotriazine–acridine conjugate

The alkylation of the specific higher-order nucleic acid structures is of great significance in order to control its function and gene expression. In this report, we have described the T–T mismatch selective alkylation with a vinyldiaminotriazine (VDAT)–acridine conjugate. The alkylation selectively proceeded at the N3 position of thymidine on the T–T mismatch. Interestingly, the alkylated thymidine induced base flipping of the complementary base in the duplex. In a model experiment for the alkylation of the CTG repeats DNA which causes myotonic dystrophy type 1 (DM1), the observed reaction rate for one alkylation increased in proportion to the number of T–T mismatches. In addition, we showed that primer extension reactions with DNA polymerase and transcription with RNA polymerase were stopped by the alkylation. The alkylation of the repeat DNA will efficiently work for the inhibition of replication and transcription reactions. These functions of the VDAT–acridine conjugate would be useful as a new biochemical tool for the study of CTG repeats and may provide a new strategy for the molecular therapy of DM1