Their findings, published recently in the journal eLife, indicate that this genetic "junk" performs the vital function of ensuring that chromosomes bundle correctly inside the cell's nucleus, which is necessary for cell survival. And this function appears to be conserved across many species. This pericentromeric satellite DNA consists of a very simple, highly repetitive sequence of genetic code. Although it accounts for a substantial portion of our genome, satellite DNA does not contain instructions for making any specific proteins.
References Abstract Hydrogen bonds provide most of the directional interactions that underpin protein folding, protein structure and molecular recognition.
Hydrogen bonding between a protein and its ligands protein, nucleic acid, substrate, effector or inhibitor provides a directionality and specificity of interaction that is a fundamental aspect of molecular recognition.
The energetics and kinetics of hydrogen bonding therefore need to be optimal to allow the rapid sampling and kinetics of folding, conferring stability to the protein structure and providing the specificity required for selective macromolecular interactions.
A hydrogen bond is formed by the interaction of a hydrogen atom that is covalently bonded to an electronegative atom donor with another electronegative atom acceptor. Hydrogen bonding confers rigidity to the protein structure and specificity to intermolecular interactions. The accepted and most frequently observed geometry for a hydrogen bond is a distance of less than 2.
On the left is the definition of geometry when proton positions are defined; on the right when they are not.
D, donor atom; A, acceptor and H, hydrogen. The plots show approximate distributions number of occurrences, N for the angle at the carbonyl oxygen O acceptor, distance between the carbonyl oxygen acceptor and amide proton H donor and the angle at the amide proton donor and carbonyl oxygen acceptor Baker and Hubbard.
The asterisk marks the serine oxygen that caps the helix. The asterisk highlights the carboxyl oxygen making a bifurcated hydrogen bond. The arrows show the direction of the polypeptide chain, emphasizing that both parallel and antiparallel strands are present in this structure.
This structure is of sufficient resolution 0. Water molecules are shown as blue spheres and hydrogen bonds as white dashed lines. The nitrogen atoms are in blue, hydrogen grey and oxygen red, with the carbon atoms of the protein in green and ligand orange.
The asterisk shows the site of linkage to the rest of the inhibitor. Details about A, B and C are discussed in the text. Journal of the American Chemical Society Progress in Biophysics and Molecular Biology Journal of Molecular Biology Protein Science 14 7: Liu Z, Wang G, Li Z and Wang R Geometrical preferences of the hydrogen bonds on protein—ligand binding interface derived from statistical surveys and quantum mechanics calculations.
Journal of Chemical Theory and Computation 4: Nature Structural Biology 6: Morokuma K Why do molecules interact?BRCA2 plays a central role in repair, which uses an undamaged sister chromatin (a family of macromolecules that consist of DNA, protein and RNA in cells) as a template for faithful repair.
DNA provides the instructions for protein synthesis- making proteins in the cell. The types of proteins a cell can make are determined by genes, which are parts of the DNA molecules in the nucleus. The order of which the bases occur is classified as the genetic code. By studying the repair of double-strand DNA breaks in vivo, evidence of a new role for the DNA-binding protein RPA has been discovered.
Researchers at the University of Michigan Life Sciences Institute and the Howard Hughes Medical Institute have determined how satellite DNA, considered to be "junk DNA," plays a crucial role in holding the genome together.
Deoxyribonucleic acid (DNA) carries the sequence of coded instructions for the synthesis of proteins, which are transcribed into ribonucleic acid (RNA) to be further translated into actual proteins. The process of protein production involves two steps: transcription and translation. Plays a key role in the initiation and regulation of chromosomal replication.
Binds in an ATP-dependent fashion to the origin of replication (oriC) to initiate formation of the DNA replication initiation complex exactly once per cell cycle.