HAMpering infection: Helicase ratcheting emerges as a phage-sensing mechanism.

The sensing of pathogens is the first step for any immune response. A recent paper in Cell reveals that the bacterial Hachiman anti-phage defense system deploys a helicase subunit to sense phage invasion via 3' DNA recognition and subsequent domain rotation to enable nuclease activation.

Catalytically active prokaryotic Argonautes employ phospholipase D family proteins to strengthen immunity against different genetic invaders.

Prokaryotic Argonautes (pAgos) provide bacteria and archaea with immunity against plasmids and viruses. Catalytically active pAgos utilize short oligonucleotides as guides to directly cleave foreign nucleic acids, while inactive pAgos lacking catalytic residues employ auxiliary effectors, such as nonspecific nucleases, to trigger abortive infection upon detection of foreign nucleic acids. Here, we report a unique group of catalytically active pAgo proteins that frequently associate with a phospholipase D (PLD) family protein.

Multilevel metabolic engineering for enhanced synthesis of S-adenosylmethionine by Bacillus amyloliquefaciens.

Objectives: To enhance the de novo synthesis of SAM, the effects of several key genes on SAM synthesis were examined based on modular strategy, and the key genes were manipulated to obtain an engineered strain with high SAM production.

Results: In Bacillus amyloliquefaciens HSAM6, the deletion of argG gene to block aspartic acid branching degradation increased SAM titer to 254.78 ± 15.

Enhancement of Green Production of Heme by Deleting Odor-Related Genes from Based on CRISPR/Cas9n.

Heme is a crucial component in endowing plant-based meat analogs with flavor and color. This study aimed to develop a green strategy for heme production by reducing fermentation off-odor and accelerating heme synthesis. First, an efficient CRISPR/Cas9n system was constructed in to construct the odor-reducing chassis cell HZC9nΔGPSU, and the odor substances including the branched-chain short fatty acids, putrescine, and ammonia were reduced by 62, 70, and 88%, respectively.

Catalytically inactive long prokaryotic Argonaute systems employ distinct effectors to confer immunity via abortive infection.

Argonaute proteins (Agos) bind short nucleic acids as guides and are directed by them to recognize target complementary nucleic acids. Diverse prokaryotic Agos (pAgos) play potential functions in microbial defense. The functions and mechanisms of a group of full-length yet catalytically inactive pAgos, long-B pAgos, remain unclear.

Effect of Composition Adjustment on the Thermoelectric Properties of MgBi-Based Thermoelectric Materials.

Thermoelectric materials are widely used in refrigeration chips, thermal power generation, catalysis and other fields. MgBi-based thermoelectric material is one of the most promising thermoelectric materials. Herein, the MgBi-based samples were prepared by high temperature synthesis, and the influence of Mg/Sb content on the electrical transport properties and semi-conductivity/semi-metallicity of the materials has been studied.

Study on the Targeted Improvement Mechanism of the Carrier Concentration and Mobility of BiCuSeO Ceramics.

BiCuSeO has great application prospects in thermoelectric power generation and thermoelectric catalysis, but it is limited by its lower thermoelectric performance. Herein, BiCuSeO bulk materials were prepared using a solid-phase reaction method and a ball-milling method combined with spark plasma sintering, and then the thermoelectric properties were improved by synergistically increasing carrier concentration and mobility. Al was adopted to dope into the BiCuSeO matrix, aiming to adjust the carrier mobility through energy band adjustment.

High-performance photocatalytic peroxymonosulfate activation by carbon quantum dots via precise surface chemistry regulation: Insight into the structure-function relations.

Carbon quantum dots (CQDs) are considered promising metal-free green catalysts for the activation of persulfates, but direct experimental evidence to identify the true active sites on the surface of CQDs is still lacking. We prepared CQDs with different oxygen contents by controlling the carbonisation temperature, using a simple pyrolysis method. Photocatalytic activity experiments show that CQDs exhibits the best PMS activation performance.

The abortive infection functions of CRISPR-Cas and Argonaute.

CRISPR-Cas and prokaryotic Argonaute (pAgo) are nucleic acid (NA)-guided defense systems that protect prokaryotes against the invasion of mobile genetic elements. Previous studies established that they are directed by NA fragments (guides) to recognize invading complementary NA (targets), and that they cleave the targets to silence the invaders. Nevertheless, growing evidence indicates that many CRISPR-Cas and pAgo systems exploit the abortive infection (Abi) strategy to confer immunity.

Genetic engineering for enhanced production of a novel alkaline protease BSP-1 in .

Alkaline protease has been widely applied in food, medicine, environmental protection and other industrial fields. However, the current activity and yield of alkaline protease cannot meet the demand. Therefore, it is important to identify new alkaline proteases with high activity.

Development and application of a rapid all-in-one plasmid CRISPR-Cas9 system for iterative genome editing in Bacillus subtilis.

Background: Bacillus subtilis, an important industrial microorganism, is commonly used in the production of industrial enzymes. Genome modification is often necessary to improve the production performance of cell. The dual-plasmid CRISPR-Cas9 system suitable for iterative genome editing has been applied in Bacillus subtilis.

The trans DNA cleavage activity of Cas12a provides no detectable immunity against plasmid or phage.

Cas12a is a type V-A CRISPR-Cas RNA-guided endonuclease. It cleaves dsDNA at specific site, and then is activated for nonspecific ssDNA cleavage in trans . The immune function of the trans activity is still unknown.

Inactivation of Target RNA Cleavage of a III-B CRISPR-Cas System Induces Robust Autoimmunity in .

Type III CRISPR-Cas systems show the target (tg)RNA-activated indiscriminate DNA cleavage and synthesis of oligoadenylates (cOA) and a secondary signal that activates downstream nuclease effectors to exert indiscriminate RNA/DNA cleavage, and both activities are regulated in a spatiotemporal fashion. In III-B Cmr systems, cognate tgRNAs activate the two Cmr2-based activities, which are then inactivated via tgRNA cleavage by Cmr4, but how Cmr4 nuclease regulates the Cmr immunization remains to be experimentally characterized. Here, we conducted mutagenesis of Cmr4 conserved amino acids in , and this revealed that Cmr4α RNase-dead (dCmr4α) mutation yields cell dormancy/death.

[Exploration and practice of synthetic biology teaching mode based on research frontiers and hotspots].

Synthetic biology, a course with a sound theoretical system and a wide application range, plays a role in the cultivation of innovative talents in the field of bioengineering. To this end, we have set up a synthetic biology course in our university. First, according to the concept of imparting basic knowledge, highlighting innovative practice, and keeping up with cutting-edge progress, we assembled a high-level teaching team for synthetic biology.

A short prokaryotic Argonaute activates membrane effector to confer antiviral defense.

Argonaute (Ago) proteins are widespread nucleic-acid-guided enzymes that recognize targets through complementary base pairing. Although, in eukaryotes, Agos are involved in RNA silencing, the functions of prokaryotic Agos (pAgos) remain largely unknown. In particular, a clade of truncated and catalytically inactive pAgos (short pAgos) lacks characterization.

Phosphorus flow analysis of different crops in Dongying District, Shandong Province, China, 1995-2016.

Investigating the phosphorus (P) sources, pathways, and final sinks are important to reduce P pollution and improve P management. In this study, substance flow analysis (SFA) was performed for P flow analysis from 1995 to 2016 in different crops of Dongying District, a core region of the alluvial delta at the estuary of the Yellow River. The results showed that P input steadily increased from 1.

Enhanced adsorption and visible-light photocatalysis on TiO with in situ formed carbon quantum dots.

Carbon quantum dots (CQDs) can be used to modify TiO to extend the light absorption threshold and enhance its photocatalytic efficiency. In this study, different amounts of CQDs modified TiO (CQDs-x/TiO) were synthesized by a facile, mild, and environmental friendly hydrothermal method at a low temperature. The physicochemical properties were investigated by a variety of advanced characterization techniques.

Expression, purification, and characterization of a membrane-associated cyclic oligo-adenylate degrader from .

Type III CRISPR-cas systems initiate cyclic oligo-adenylate (cOA) signaling to initiate immune response. Previously, we identified that a membrane-associated DHH-DHHA1 family protein from efficiently degrades cOA. Here, we provide detailed protocols for expression and purification of the protein from its native host and a cOA degradation assay with the purified enzyme.

CRISPR-Associated Factor Csa3b Regulates CRISPR Adaptation and Cmr-Mediated RNA Interference in .

Acquisition of spacers confers the CRISPR-Cas system with the memory to defend against invading mobile genetic elements. We previously reported that the CRISPR-associated factor Csa3a triggers CRISPR adaptation in . However, a feedback regulation of CRISPR adaptation remains unclear.

A Membrane-Associated DHH-DHHA1 Nuclease Degrades Type III CRISPR Second Messenger.

Type III CRISPR-Cas systems initiate an intracellular signaling pathway to confer immunity. The signaling pathway includes synthesis of cyclic oligo-adenylate (cOA) and activation of the RNase activity of type III accessory ribonuclease Csm6/Csx1 by cOA. After the immune response, cOA should be cleared on time to avoid constant cellular RNA degradation.

A Unique B-Family DNA Polymerase Facilitating Error-Prone DNA Damage Tolerance in Crenarchaeota.

codes for four DNA polymerases: three are of the B-family (Dpo1, Dpo2, and Dpo3), and one is of the Y-family (Dpo4). Western analysis revealed that among the four polymerases, only Dpo2 exhibited DNA damage-inducible expression. To investigate how these DNA polymerases could contribute to DNA damage tolerance in , we conducted genetic analysis of their encoding genes in this archaeon.

Photocatalytic activation of peroxymonosulfate by surface-tailored carbon quantum dots.

In this study, carbon quantum dots (CQDs) were synthesized by a low-cost and scalable approach and the oxygen functional groups were fine-tuned by chemical post-treatment. It was found that the CQDs could be applied as visible-light-responsive photocatalysts for activation of peroxymonosulfate (PMS) and remediation of aqueous organic dyes. Phenylhydrazine modified CQDs (CQDs-PH) presented high efficiency for degradation of methylene blue due to selective removal of carboxylic groups and inhibited recombination of photogenerated electron-hole pairs.

Cmr3 regulates the suppression on cyclic oligoadenylate synthesis by tag complementarity in a Type III-B CRISPR-Cas system.

Type III CRISPR-Cas systems code for a multi-subunit ribonucleoprotein (RNP) complex that mediates DNA cleavage and synthesizes cyclic oligoadenylate (cOA) second messenger to confer anti-viral immunity. Both immune activities are to be activated upon binding to target RNA transcripts by their complementarity to crRNA, and autoimmunity avoidance is determined by extended complementarity between the 5'-repeat tag of crRNA and 3'-flanking sequences of target transcripts (anti-tag). However, as to how the strategy could achieve stringent autoimmunity avoidance remained elusive.

Design and Synthesis of a New Mannitol Stearate Ester-Based Aluminum Alkoxide as a Novel Tri-Functional Additive for Poly(Vinyl Chloride) and Its Synergistic Effect with Zinc Stearate.

Thermal stabilizers, lubricant, and plasticizers are three crucial additives for processing poly(vinyl chloride) (PVC). In this study, a new mannitol stearate ester-based aluminum alkoxide (MSE-Al) was designed and synthesized as a novel additive for PVC. The thermal stability and processing performance of PVC stabilized by MSE-Al were evaluated by the Congo red test, conductivity measurement, thermal aging test, ultravioletevisible (UV-Vis) spectroscopy test, and torque rheometer test.