Cell type-specific 3D-genome organization and transcription regulation in the brain.

3D organization of the genome plays a critical role in regulating gene expression. How 3D-genome organization differs among different cell types and relates to cell type-dependent transcriptional regulation remains unclear. Here, we used genome-scale DNA and RNA imaging to investigate 3D-genome organization in transcriptionally distinct cell types in the mouse cerebral cortex.

Allosteric communication in DNA polymerase clamp loaders relies on a critical hydrogen-bonded junction.

Clamp loaders are AAA+ ATPases that load sliding clamps onto DNA. We mapped the mutational sensitivity of the T4 bacteriophage sliding clamp and clamp loader by deep mutagenesis, and found that residues not involved in catalysis or binding display remarkable tolerance to mutation. An exception is a glutamine residue in the AAA+ module (Gln 118) that is not located at a catalytic or interfacial site.

Transmembrane Helices Tilt, Bend, Slide, Torque, and Unwind between Functional States of Rhodopsin.

The seven-helical bundle of rhodopsin and other G-protein coupled receptors undergoes structural rearrangements as the transmembrane receptor protein is activated. These structural changes are known to involve tilting and bending of various transmembrane helices. However, the cause and effect relationship among structural events leading to a cytoplasmic crevasse for G-protein binding is less well defined.