Mechanistic Insight into the Enantioselective Degradation of Esterase QeH to (R)/(S)-Quizalofop-Ethyl with Molecular Dynamics Simulation Using a Residue-Specific Force Field.

The enantioselective mechanism of the esterase QeH against the two enantiomers of quizalofop-ethyl (QE) has been primitively studied using computational and experimental approaches. However, it is still unclear how the esterase QeH adjusts its conformation to adapt to substrate binding and promote enzyme-substrate interactions in the catalytic kinetics. The equilibrium processes of enzyme-substrate interactions and catalytic dynamics were reproduced by performing independent molecular dynamics (MD) runs on the QeH-(R)/(S)-QE complexes with a newly developed residue-specific force field (RSFF2C). Our results indicated that the benzene ring of the (R)-QE structure can simultaneously form anion-π and cation-π interactions with the side-chain group of Glu328 and Arg384 in the binding cavity of the QeH-(R)-QE complex, resulting in (R)-QE being closer to its catalytic triplet system (Ser78-Lys81-Tyr189) with the distances measured for the hydroxyl oxygen atom of the catalytic Ser78 of QeH and the carbonyl carbon atom of (R)-QE of 7.39 Å, compared to the 8.87 Å for (S)-QE, whereas the (S)-QE structure can only form an anion-π interaction with the side chain of Glu328 in the QeH-(S)-QE complex, being less close to its catalytic site. The computational alanine scanning mutation (CAS) calculations further demonstrated that the π-π stacking interaction between the indole ring of Trp351 and the benzene ring of (R)/(S)-QE contributed a lot to the binding stability of the enzyme-substrate (QeH-(R)/(S)-QE). These results facilitate the understanding of their catalytic processes and provide new theoretical guidance for the directional design of other key enzymes for the initial degradation of aryloxyphenoxypropionate (AOPP) herbicides with higher catalytic efficiencies.

Novel coronavirus mutations: Vaccine development and challenges.

The ongoing global pandemic of novel coronavirus pneumonia (COVID-19) caused by the SARS-CoV-2 has a significant impact on global health and economy system. In this context, there have been some landmark advances in vaccine development. Over 100 new coronavirus vaccine candidates have been approved for clinical trials, with ten WHO-approved vaccines including four inactivated virus vaccines, two mRNA vaccines, three recombinant viral vectored vaccines and one protein subunit vaccine on the "Emergency Use Listing". Although the SARS-CoV-2 has an internal proofreading mechanism, there have been a number of mutations emerged in the pandemic affecting its transmissibility, pathogenicity and immunogenicity. Of these, mutations in the spike (S) protein and the resultant mutant variants have posed new challenges for vaccine development and application. In this review article, we present an overview of vaccine development, the prevalence of new coronavirus variants and their impact on protective efficacy of existing vaccines and possible immunization strategies coping with the viral mutation and diversity.

Bulk Mn2+ Doped 1D Hybrid Lead Halide Perovskite with Highly Efficient, Tunable and Stable Broadband Light Emissions.

Mn2+ doped colloidal three-dimensional (3D) lead halide perovskite nanocrystal (PNC) has attracted intensive research attention; however, the low exciton binding energy and fatal optical instability of 3D PNC seriously hinder the optoelectronic application. Therefore, it remains significant to explore new stable host perovskite with strongly bound exciton to realize more desirable luminescent property. In this work, we utilized bulk one-dimensional (1D) hybrid perovskite of [AEP]PbBr5 ⋅ H2 O (AEP=N-aminoethylpiperazine) as structural platform to rationally optimize the luminescent property by a controllable Mn2+ doping strategy. Significantly, the series of Mn2+ -doped 1D [AEP]PbBr5 ⋅ H2 O show enhanced energy transfer efficiency from the strongly bound excitons of host material to 3d electrons of Mn2+ ions, resulting in tunable broadband light emissions from weak yellow to strong red spectral range with highest photoluminescence quantum yield up to 28.41 %. More importantly, these Mn2+ -doped 1D perovskites display ultrahigh structural and optical stabilities in humid atmosphere, water and high temperature exceeding the conventional 3D PNC. Combined highly efficient, tunable and stable broadband light emissions enable Mn2+ -doped 1D perovskite as excellent down-converting phosphor showcasing the potential application in white light emitting diode. This work not only provides a profound understanding of low-dimensional perovskites but also opens a new way to rationally design high-performance broadband light emitting perovskites for solid-state lighting and displaying devices.

Ultra-Sensitive, Selective and Repeatable Fluorescence Sensor for Methanol Based on a Highly Emissive 0D Hybrid Lead-Free Perovskite.

A convenient and rapid detection method for methanol in ethanol remains a major challenge due to their indistinguishable physical properties. Herein, a novel fluorescence probe based on perovskite was successfully designed to overcome this bottleneck. We report a new zero-dimensional (0D) hybrid perovskite of [MP]2 Inx Sb1-x Cl7 ⋅ 6 H2 O (MP=2-methylpiperazine) displaying an unusual green light emission with near-unity photoluminescence quantum yield. Remarkably, this 0D perovskite exhibits reversible methanol-response luminescence switching between green and yellow color but fail in any other organic vapors. Even for blended alcohol solutions, the luminescent probe exhibits excellent sensing performance with multiple superiorities of rapid response time (30 s) and ultra-low detection limit (40 ppm), etc. Therefore, this 0D perovskite can be utilized as a perfect fluorescence probe to detect traces of methanol from ethanol with ultrahigh sensitivity, selectivity and repeatability. To the best of our knowledge, this work represents the first perovskite as fluorescence probe for methanol with wide potential in environmental monitoring and methanol detection, etc.

Three-Dimensional Cuprous Iodide Framework with Intrinsic Broadband Red-to-Near-Infrared Light Emission.

Herein, a new organic-inorganic hybrid cuprous iodide of [(Me)2-DABCO]Cu6I8 was prepared and structurally characterized with a novel three-dimensional (3D) [Cu6I8]2- framework. Significantly, this 3D cuprous iodide displays infrequent broadband red-to-near-infrared light emission (600-1000 nm) stemming from the radiative recombination of self-trapped excitons.

Cellulomonas shaoxiangyii sp. nov., isolated from faeces of Tibetan antelope (Pantholops hodgsonii) on the Qinghai-Tibet Plateau.

Two Gram-stain-positive, catalase-positive and oxidase-negative, aerobic, non-motile, cellobiose-utilizing, short-rod-shaped strains (Z28T and Z29) were isolated from faeces of Tibetan antelope (Pantholops hodgsonii) collected on the Qinghai-Tibet Plateau. Strain Z28T shared 98.1, 98.0, 97.8 and 97.4 % 16S rRNA gene similarity, 24.1, 22.8, 23.2 and 26.3 % digital DNA-DNA hybridization relatedness and 80.8, 80.0, 80.7 and 80.9 % average nucleotide identity values with Cellulomonas oligotrophica DSM 24482T, Cellulomonas flavigena DSM 20109T, Cellulomonas iranensis DSM 14785T and Cellulomonas terrae JCM 14899T, respectively. Results from further phylogenetic analyses based on the 16S rRNA gene and 148 core genes indicated that strains Z28T and Z29 were closest to C. oligotrophica DSM 24482T and C. flavigena DSM 20109T, but clearly separated from the currently recognized species of the genus Cellulomonas. The genomic DNA G+C content of strain Z28T was 75.3 mol%. The major cellular fatty acids were anteiso-C15 : 0, anteiso-C15 : 1 A, C16 : 0 and anteiso-C17 : 0. Ribose and mannose were detected as the whole-cell sugars. The major respiratory quinone was MK-9(H4) and ornithine was the diamino acid of the cell wall. The polar lipids present in strain Z28T were phosphatidylethanolamine, five phospholipids, two aminophospholipids, aminolipid and three unidentified lipids. Comparison of phenotypic and phylogenetic features between the two strains and the related organisms revealed that Z28T and Z29 represent a novel species of the genus Cellulomonas, for which the name Cellulomonas shaoxiangyii sp. nov. is proposed. The type strain is Z28T (=CGMCC 1.16477T=DSM 106200T).

Roseomonas wenyumeiae sp. nov., isolated from faeces of Tibetan antelopes (Pantholops hodgsonii) on the Qinghai-Tibet Plateau.

Two Gram-stain-negative, catalase- and oxidase-positive, non-spore-forming, aerobic, motile, flagellated, and coccus-shaped strains (Z23T and Z24) were isolated from faeces of Tibetan antelopes (Pantholops hodgsonii) on the Qinghai-Tibet Plateau, PR China. Results of the morphological, biochemical, and phylogenetic studies indicated that they were similar to each other, but distinct from existing species of the genus Roseomonas. The proposed type strain, Z23T, had 97.8, 97.1 and 96.8 % 16S rRNA similarity to Roseomonas ludipueritiae DSM 14915T, Roseomonas aerofrigidensis JCM 31878T and Roseomonas aerophila KACC 16529T. Results from further phylogenetic analyses based on the 16S rRNA gene and 857 core genes indicated that the two strains were members of Roseomonas, but clearly separated from the currently recognized species. Strains Z23T had 43.8 %, 25.0 % DNA-DNA relatedness and 91.2, 81.3 % ANI values with R. ludipueritiae DSM 14915T and R. aerophila KACC 16529T. The genomic DNA G+C content of strain Z23T was 68.6 mol%. The major cellular fatty acids of strain Z23T were C18 : 1ω7c and/or C18 : 1ω6c and C19 : 0cyclo ω8c. The cell-wall sugars included glucose, rhamnose and ribose. Q-10 was the sole respiratory quinone, and spermidine was the major polyamine component. Polar lipids present in strain Z23T were phosphatidylcholine, diphosphatidylglycerol, phosphatidylethanolamine, aminophospholipid, phosphatidylglycerol, three aminolipids, two phospholipids and two unidentified lipids. Based on the distinct differences from other Roseomonas species judged from the genotypic and phenotypic data, a novel species represented by Z23T and Z24, Roseomonas wenyumeiae sp. nov., is proposed. The type strain is Z23T (=CGMCC 1.16540T=DSM 106207T).

Streptococcus chenjunshii sp. nov. isolated from feces of Tibetan antelopes.

Three Gram-stain-positive, catalase-negative, α-haemolytic, chain-forming and coccus-shaped microorganisms (strains Z15T, Z1 and Z2) were isolated from feces of Tibetan antelopes collected from the Qinghai-Tibet plateau, PR China. The results of 16S rRNA gene sequence studies indicated that Z15T shared 94.5, 93.1 and 92.2 % similarity with Streptococcus pantholopis DSM 102135T, Streptococcus ursoris NUM 1615T and Streptococcus dentapri NUM 1529T, respectively. rpoB and groEL-based sequence analysis of our three novel isolates revealed interspecies divergence of 16.7 and 14.3 % from Streptococcus pantholopis DSM 102135T. The genomic DNA G+C content of Z15T is 42.48 mol%. Z15T has an average nucleotide identity (ANI) value of 81.19 % with S. pantholopis DSM 102135T and a DNA-DNA relatedness value of less than 70 % in the in-silico DNA-DNA hybridization (isDDH) with other species of genus Streptococcus deposited in the GenBank database. A whole-genome phylogenetic tree based on 246 core genes of 78 genomes of members of the genus Streptococcusindicated that Z15T represents a member of genus Streptococcus but one well separated from the currently recognized species. Z15T contains C18 : 1ω7c (25.5 %), C18 : 1ω9c (19.6 %), C16 : 0 (17.5 %) and C16 : 1ω9c (13.3 %) as its major cellular fatty acids. According to the morphological, biochemical and molecular phylogenetic features of the three novel isolates, they represent a novel species of the genus Streptococcus, and Streptococcus chenjunshii sp. nov. is thus proposed. The type strain is Z15T (=CGMCC 1.16529=DSM 106182).

Spatial organization of enzymes to enhance synthetic pathways in microbial chassis: a systematic review.

For years, microbes have been widely applied as chassis in the construction of synthetic metabolic pathways. However, the lack of in vivo enzyme clustering of heterologous metabolic pathways in these organisms often results in low local concentrations of enzymes and substrates, leading to a low productive efficacy. In recent years, multiple methods have been applied to the construction of small metabolic clusters by spatial organization of heterologous metabolic enzymes. These methods mainly focused on using engineered molecules to bring the enzymes into close proximity via different interaction mechanisms among proteins and nucleotides and have been applied in various heterologous pathways with different degrees of success while facing numerous challenges. In this paper, we mainly reviewed some of those notable advances in designing and creating approaches to achieve spatial organization using different intermolecular interactions. Current challenges and future aspects in the further application of such approaches are also discussed in this paper.

The cotton MYB108 forms a positive feedback regulation loop with CML11 and participates in the defense response against Verticillium dahliae infection.

Accumulating evidence indicates that plant MYB transcription factors participate in defense against pathogen attack, but their regulatory targets and related signaling processes remain largely unknown. Here, we identified a defense-related MYB gene (GhMYB108) from upland cotton (Gossypium hirsutum) and characterized its functional mechanism. Expression of GhMYB108 in cotton plants was induced by Verticillium dahliae infection and responded to the application of defense signaling molecules, including salicylic acid, jasmonic acid, and ethylene. Knockdown of GhMYB108 expression led to increased susceptibility of cotton plants to V. dahliae, while ecotopic overexpression of GhMYB108 in Arabidopsis thaliana conferred enhanced tolerance to the pathogen. Further analysis demonstrated that GhMYB108 interacted with the calmodulin-like protein GhCML11, and the two proteins form a positive feedback loop to enhance the transcription of GhCML11 in a calcium-dependent manner. Verticillium dahliae infection stimulated Ca(2+) influx into the cytosol in cotton root cells, but this response was disrupted in both GhCML11-silenced plants and GhMYB108-silenced plants in which expression of several calcium signaling-related genes was down-regulated. Taken together, these results indicate that GhMYB108 acts as a positive regulator in defense against V. dahliae infection by interacting with GhCML11. Furthermore, the data also revealed the important roles and synergetic regulation of MYB transcription factor, Ca(2+), and calmodulin in plant immune responses.