scholarly journals The novel anti-CRISPR AcrIIA22 relieves DNA torsion in target plasmids and impairs SpyCas9 activity

PLoS Biology ◽  
2021 ◽  
Vol 19 (10) ◽  
pp. e3001428
Author(s):  
Kevin J. Forsberg ◽  
Danica T. Schmidtke ◽  
Rachel Werther ◽  
Ruben V. Uribe ◽  
Deanna Hausman ◽  
...  
Keyword(s):  
The Novel ◽  
Nucleic Acid Binding ◽  
Human Gut ◽  
X Ray ◽  
Defense Systems ◽  
Nucleic Acid Binding Proteins ◽  
Genomic Regions ◽  
Insight Into ◽  
Negative Supercoils ◽  
Cas Proteins

To overcome CRISPR-Cas defense systems, many phages and mobile genetic elements (MGEs) encode CRISPR-Cas inhibitors called anti-CRISPRs (Acrs). Nearly all characterized Acrs directly bind Cas proteins to inactivate CRISPR immunity. Here, using functional metagenomic selection, we describe AcrIIA22, an unconventional Acr found in hypervariable genomic regions of clostridial bacteria and their prophages from human gut microbiomes. AcrIIA22 does not bind strongly to SpyCas9 but nonetheless potently inhibits its activity against plasmids. To gain insight into its mechanism, we obtained an X-ray crystal structure of AcrIIA22, which revealed homology to PC4-like nucleic acid–binding proteins. Based on mutational analyses and functional assays, we deduced that acrIIA22 encodes a DNA nickase that relieves torsional stress in supercoiled plasmids. This may render them less susceptible to SpyCas9, which uses free energy from negative supercoils to form stable R-loops. Modifying DNA topology may provide an additional route to CRISPR-Cas resistance in phages and MGEs.

scholarly journals AcrIIA22 is a novel anti-CRISPR that impairs SpyCas9 activity by relieving DNA torsion of target plasmids

2020 ◽  
Author(s):  
Kevin J. Forsberg ◽  
Danica T. Schmidtke ◽  
Rachel Werther ◽  
Deanna Hausman ◽  
Barry L. Stoddard ◽  
...  
Keyword(s):  
Mobile Genetic Elements ◽  
Nucleic Acid Binding ◽  
Human Gut ◽  
X Ray ◽  
Genetic Elements ◽  
Defense Systems ◽  
Nucleic Acid Binding Proteins ◽  
Genomic Regions ◽  
Insight Into ◽  
Negative Supercoils

AbstractTo overcome CRISPR-Cas defense systems, many phages and mobile genetic elements encode CRISPR-Cas inhibitors called anti-CRISPRs (Acrs). Nearly all mechanistically characterized Acrs directly bind their cognate Cas protein to inactivate CRISPR immunity. Here, we describe AcrIIA22, an unconventional Acr found in hypervariable genomic regions of Clostridial bacteria and their prophages from the human gut microbiome. Uncovered in a functional metagenomic selection, AcrIIA22 does not bind strongly to SpyCas9 but nonetheless potently inhibits its activity against plasmids. To gain insight into its mechanism, we obtained an X-ray crystal structure of AcrIIA22, which revealed homology to PC4-like nucleic-acid binding proteins. This homology helped us deduce that acrIIA22 encodes a DNA nickase that relieves torsional stress in supercoiled plasmids, rendering them less susceptible to SpyCas9, which is highly dependent on negative supercoils to form stable R-loops. Modifying DNA topology may provide an additional route to CRISPR-Cas resistance in phages and mobile genetic elements.

The characteristic radiation of copper Kα1,2,3,4

2019 ◽  
Vol 75 (3) ◽  
pp. 527-540 ◽  
Author(s):  
Hamish A. Melia ◽  
Christopher T. Chantler ◽  
Lucas F. Smale ◽  
Alexis J. Illig
Keyword(s):  
The Novel ◽  
Double Crystal ◽  
Satellite Line ◽  
X Ray ◽  
Double Crystal Monochromator ◽  
Alternative Approaches ◽  
Integrated Intensities ◽  
Spectral Characterizations ◽  
Insight Into

A characterization of the Cu Kα1,2 spectrum is presented, including the 2p satellite line, Kα3,4, the details of which are robust enough to be transferable to other experiments. This is a step in the renewed attempts to resolve inconsistencies in characteristic X-ray spectra between theory, experiment and alternative experimental geometries. The spectrum was measured using a rotating anode, monolithic Si channel-cut double-crystal monochromator and backgammon detector. Three alternative approaches fitted five Voigt profiles to the data: a residual analysis approach; a peak-by-peak fit; and a simultaneous constrained method. The robustness of the fit is displayed across three spectra obtained with different instrumental broadening. Spectra were not well fitted by transfer of any of three prior characterizations from the literature. Integrated intensities, line widths and centroids are compared with previous empirical fits. The novel experimental setup provides insight into the portability of spectral characterizations of X-ray spectra. From the parameterization, an estimated 3d shake probability of 18% and a 2p shake probability of 0.5% are reported.

Quantitative Analysis Of X-Ray Images From Geological Materials

1990 ◽  
Vol 48 (2) ◽  
pp. 244-245
Author(s):  
J. M. Paque ◽  
R. Browning ◽  
P. L. King ◽  
P. Pianetta
Keyword(s):  
Quantitative Analysis ◽  
Bulk Composition ◽  
Principal Component ◽  
Analytical Description ◽  
Bulk Sample ◽  
Geological Samples ◽  
X Ray ◽  
Software And Hardware ◽  
And Storage ◽  
Insight Into

Geological samples typically contain many minerals (phases) with multiple element compositions. A complete analytical description should give the number of phases present, the volume occupied by each phase in the bulk sample, the average and range of composition of each phase, and the bulk composition of the sample. A practical approach to providing such a complete description is from quantitative analysis of multi-elemental x-ray images.With the advances in recent years in the speed and storage capabilities of laboratory computers, large quantities of data can be efficiently manipulated. Commercial software and hardware presently available allow simultaneous collection of multiple x-ray images from a sample (up to 16 for the Kevex Delta system). Thus, high resolution x-ray images of the majority of the detectable elements in a sample can be collected. The use of statistical techniques, including principal component analysis (PCA), can provide insight into mineral phase composition and the distribution of minerals within a sample.

Copper–oxygen Dynamics in Tyrosinase

2019 ◽  
Author(s):  
Nobutaka Fujieda ◽  
Sachiko Yanagisawa ◽  
Minoru Kubo ◽  
Genji Kurisu ◽  
Shinobu Itoh
Keyword(s):  
Catalytic Mechanism ◽  
Substrate Binding ◽  
Active Form ◽  
Copper Ion ◽  
Atomic Resolution ◽  
Oxygen Species ◽  
X Ray ◽  
Oxygen Dynamics ◽  
Insight Into ◽  
Copper Centre

To unveil the activation of dioxygen on the copper centre (Cu<sub>2</sub>O<sub>2</sub>core) of tyrosinase, we performed X-ray crystallograpy with active-form tyrosinase at near atomic resolution. This study provided a novel insight into the catalytic mechanism of the tyrosinase, including the rearrangement of copper-oxygen species as well as the intramolecular migration of copper ion induced by substrate-binding.<br>

Ten-Vertex Polyhedral Monocarbaborane Chemistry. The Novel High-Yield Formation of the Ten-Vertex closo Compound [6-(PMe2Ph)-closo-1-CB9H9] from the Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11]

1993 ◽  
Vol 58 (12) ◽  
pp. 2924-2935 ◽  
Author(s):  
Jane H. Jones ◽  
Bohumil Štíbr ◽  
John D. Kennedy ◽  
Mark Thornton-Pett
Keyword(s):  
Nmr Spectroscopy ◽  
Diffraction Analysis ◽  
High Yield ◽  
Monoclinic Space Group ◽  
The Novel ◽  
X Ray Diffraction ◽  
Metal Centre ◽  
X Ray ◽  
Yield Formation ◽  
Boiling Toluene

Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11] in boiling toluene solution results in an elimination of the platinum centre and cluster closure to give the ten-vertex closo species [6-(PMe2Ph)-closo-1-CB9H9] in 85% yield as a colourles air stable solid. The product is characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Crystals (from hexane-dichloromethane) are monoclinic, space group P21/c, with a = 903.20(9), b = 1 481.86(11), c = 2 320.0(2) pm, β = 97.860(7)° and Z = 8, and the structure has been refined to R(Rw) = 0.045(0.051) for 3 281 observed reflections with Fo > 2.0σ(Fo). The clean high-yield elimination of a metal centre from a polyhedral metallaborane or metallaheteroborane species is very rare.

The Monk

2016 ◽  
Author(s):  
Matthew Lewis
Keyword(s):  
French Revolution ◽  
English Literature ◽  
Young Girl ◽  
The Novel ◽  
Reading Public ◽  
Ghost Stories ◽  
Gothic Fiction ◽  
Black Magic ◽  
Insight Into ◽  
Profound Insight

‘He was deaf to the murmurs of conscience, and resolved to satisfy his desires at any price.’ The Monk (1796) is a sensational story of temptation and depravity, a masterpiece of Gothic fiction and the first horror novel in English literature. The respected monk Ambrosio, the Abbot of a Capuchin monastery in Madrid, is overwhelmed with desire for a young girl; once having abandoned his monastic vows he begins a terrible descent into immorality and violence. His appalling fall from grace embraces blasphemy, black magic, torture, rape, and murder, and places his very soul in jeopardy. Lewis’s extraordinary tale drew on folklore, legendary ghost stories, and contemporary dread inspired by the terrors of the French Revolution. Its excesses shocked the reading public and it was condemned as obscene. The novel continues to beguile and shock readers today with its gruesome catalogue of iniquities, while at the same time giving a profound insight into the deep anxieties experienced by British citizens during one of the most turbulent periods in the nation’s history.

scholarly journals Some Novel Cobalt Diphenylphosphine Complexes: Synthesis, Characterization, and Behavior in the Polymerization of 1,3-Butadiene

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4067
Author(s):  
Giovanni Ricci ◽  
Giuseppe Leone ◽  
Giorgia Zanchin ◽  
Benedetta Palucci ◽  
Alessandra Forni ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
And Behavior

Some novel cobalt diphenylphosphine complexes were synthesized by reacting cobalt(II) chloride with (2-methoxyethyl)diphenylphosphine, (2-methoxyphenyl)diphenylphosphine, and 2-(1,1-dimethylpropyl)-6-(diphenylphosphino)pyridine. Single crystals suitable for X-ray diffraction studies were obtained for the first two complexes, and their crystal structure was determined. The novel compounds were then used in association with methylaluminoxane (MAO) for the polymerization of 1,3-butadiene, and their behavior was compared with that exhibited in the polymerization of the same monomer by the systems CoCl2(PnPrPh2)2/MAO and CoCl2(PPh3)2/MAO. Some significant differences were observed depending on the MAO/Co ratio used, and a plausible interpretation for such a different behavior is proposed.

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