Structural Investigations on the Interactions between Cytidine Deaminase Human APOBEC3G and DNA

2019 ◽  
Vol 14 (13) ◽  
pp. 2235-2241 ◽  
Author(s):  
Xiaoxuan Yan ◽  
Wenxian Lan ◽  
Chunxi Wang ◽  
Chunyang Cao
Keyword(s):  
Cytidine Deaminase ◽  
Structural Investigations ◽  
Human Apobec3g

scholarly journals Highly precise base editing with CC context-specificity using engineered human APOBEC3G-nCas9 fusions

2019 ◽  
Author(s):  
Zhiquan Liu ◽  
Siyu Chen ◽  
Huanhuan Shan ◽  
Mao Chen ◽  
Yuning Song ◽  
...  
Keyword(s):  
Cytidine Deaminase ◽  
Context Specificity ◽  
Gene Modification ◽  
Base Editing ◽  
Human Apobec3g ◽  
Activity Window

AbstractCytidine base editors, composed of a cytidine deaminase fused to Cas9 nickase, enable efficient C-to-T conversion in various organisms. However, current base editors can induce unwanted bystander C-to-T conversions when more than one C is present in the activity window of cytidine deaminase, which negatively affects the precision. Here, we develop a new base editor with CC context-specificity using rationally engineered human APOBEC3G, thus significantly reduce unwanted bystander activities. In addition, efficient C-to-T conversion that can further recognize relaxed NG PAMs is achieved by combining an engineered SpCas9-NG variant. These novel base editors with improved precision and targeting scope will expand the toolset for precise gene modification in organisms.

Observation of biological macromolecules using various electron microscopic methods

1978 ◽  
Vol 36 (2) ◽  
pp. 170-171
Author(s):  
Mitsuo Ohtsuki ◽  
Michael Sogard
Keyword(s):  
Electron Microscope ◽  
Phase Contrast ◽  
Image Interpretation ◽  
Density Lipoprotein ◽  
Biological Macromolecules ◽  
Contrast Effects ◽  
Biological Structure ◽  
Electron Microscopic ◽  
Structural Investigations ◽  
Staining Techniques

Structural investigations of biological macromolecules commonly employ CTEM with negative staining techniques. Difficulties in valid image interpretation arise, however, due to problems such as variability in thickness and degree of penetration of the staining agent, noise from the supporting film, and artifacts from defocus phase contrast effects. In order to determine the effects of these variables on biological structure, as seen by the electron microscope, negative stained macromolecules of high density lipoprotein-3 (HDL3) from human serum were analyzed with both CTEM and STEM, and results were then compared with CTEM micrographs of freeze-etched HDL3. In addition, we altered the structure of this molecule by digesting away its phospholipid component with phospholipase A2 and look for consistent changes in structure.

A tilting high temperature gas reaction chamber for the JEM 7A T.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 70-71
Author(s):  
Brian L. Rhoades
Keyword(s):  
Cross Section ◽  
Reaction Chamber ◽  
Objective Lens ◽  
Reduced Cross Section ◽  
Cross Sectional ◽  
Structural Investigations ◽  
Transmission Electron ◽  
Dynamic Experiments ◽  
Successful Design ◽  
Thermocouple Junction

A gas reaction chamber has been designed and constructed for the JEM 7A transmission electron microscope which is based on a notably successful design by Hashimoto et. al. but which provides specimen tilting facilities of ± 15° aboutany axis in the plane of the specimen.It has been difficult to provide tilting facilities on environmental chambers for 100 kV microscopes owing to the fundamental lack of available space within the objective lens and the scope of structural investigations possible during dynamic experiments has been limited with previous specimen chambers not possessing this facility.A cross sectional diagram of the specimen chamber is shown in figure 1. The specimen is placed on a platinum ribbon which is mounted on a mica ring of the type shown in figure 2. The ribbon is heated by direct current, and a thermocouple junction spot welded to the section of the ribbon of reduced cross section enables temperature measurement at the point where localised heating occurs.

Cloning, expression and structural investigations of P5βR-like enone reductases from various

Planta Medica ◽  
2010 ◽  
Vol 76 (12) ◽  
Author(s):  
P Bauer ◽  
M Brydziun ◽  
F Müller-Uri ◽  
W Kreis
Keyword(s):  
Structural Investigations
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