Dendrohyrax interfluvialis lives in the wet and dry forests that lie between the two rivers in coastal regions of southeastern Ghana, southern Togo and Benin, and southwestern Nigeria. Dendrohyrax interfluvialis. Image credit: Oates et al., doi: 10.1093/zoolinnean/zlab029. Tree hyraxes (genus Dendrohyrax) are one of only three genera currently recognized in Procaviidae, the only extant family in the mammalian order Hyracoidea. Also known as tree dassie,...
Biology News
![Ternary structure of Polθ on a DNA/RNA primer-template: (A) Polθ polymerase; (B) DNA/RNA extension by Polθ and PolθΔL; (C) structure of Polθ:DNA/RNA:ddGTP; (D) superposition of Polθ:DNA/RNA (marine) and Polθ:DNA/DNA (orange, 4x0q); the fingers and thumb subdomains undergo reconfiguration; (E) superposition of Polθ:DNA/RNA (marine) and Polθ:DNA/DNA (orange, 4x0q) highlighting a 12-Å shift of K2181 (blue box; thumb) and a 4.4-Å shift of E2246 (gray box; palm); (F) superposition of nucleic acids and ddGTP from Polθ:DNA/RNA:ddGTP and Polθ:DNA/DNA:ddGTP structures; (G) top: electron density of ddGTP and 3′ primer terminus in Polθ:DNA/RNA structure; bottom: zoomed-in image of the superposition of active sites, illustrating a different conformation of ddGTP in the Polθ:DNA/RNA (blue) and Polθ:DNA/DNA (salmon) complexes; (H) interactions between ribose 2’-hydroxyl groups of the RNA template and residues in the Polθ:DNA/RNA structure; red dashed lines, hydrogen bonds; (I) DNA/RNA used for cocrystallization with Polθ and ddGTP (top); strong electron density is present for four base pairs [nucleotides located at positions 2 to 5 (underlined) of the DNA/RNA] and two base pairs resulting from an incorporated ddGMP (2’,3’ dideoxyguanosine monophosphate) (green; position 1) and a bound unincorporated ddGTP (red; position 0) in the active site (top); interactions between Polθ and nucleic acids in Polθ:DNA/RNA:ddGTP (bottom); interactions between residues and phosphate backbone, sugar oxygen, or nucleobase are shown in blue, yellow, and green, respectively; hydrogen bonds between Polθ and ribose 2’-hydroxyl groups are indicated (boxed residues); (J) interactions between Polθ and nucleic acids in Polθ:DNA/DNA:ddGTP (4x0q); color scheme identical to (I). Image credit: Chandramouly et al., doi: 10.1126/sciadv.abf1771.](https://cdn.sci.news/images/2021/06/image_9759-Polymerase-Theta-195x110.jpg)
