Genome complexity: how a cell nucleus offers gene info (Introduction)

by David Turell , Tuesday, June 22, 2021, 22:17 (1032 days ago) @ David Turell

Very complex, highly controlled system:

https://www.sciencedaily.com/releases/2021/06/210622142832.htm

"Almost all cells in our body contain a nucleus: a somewhat spherical structure that is separated from the rest of the cell by a membrane. Each nucleus contains all the genetic information of the human being. So it serves as a kind of library -- but one with strict requirements: If the cell needs the building instructions for a protein, it won't simply borrow the original information. Instead, a transcript of it is made in the nucleus.

"The machinery required for this is very complex, not least because the transcripts are not simple copies. In addition to essential information, genes also contain numerous passages of meaningless "garbage." They are removed when the transcript is made. Biologists call this editorial revision "splicing."

"'An important role in splicing is played by the SMN complex, a 'molecular machine' consisting of nine different proteins," explains Prof. Dr. Oliver Gruss from the Institute of Genetics at the University of Bonn, who is also a member of the university's transdisciplinary research area "Life and Health." "Interestingly, these machines are not evenly distributed in the nucleus. Instead, they accumulate at specific sites called Cajal bodies." However, there are no transport mechanisms in the cell nucleus that bring the SMN complexes to Cajal bodies. Instead, the SMN proteins themselves have certain properties that are responsible for their aggregation.

"SMN complexes have a prominent feature: They carry an unusually large number of phosphate groups, which are small molecular residues with a phosphorus atom in the center. "We suspected that this phosphorylation promotes their mass clustering into Cajal bodies," explains Dr. Maximilian Schilling from the research group around Oliver Gruss.

"Phosphate groups are not part of the actual blueprint of a protein -- they are added later and can also be removed again. This is often how the cell regulates the activity of the respective protein. The phosphate group is attached in this process by certain enzymes, the kinases.

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"In this way, they encountered a network of kinases, which, when inhibited, caused the Cajal bodies to largely disappear. Further analyses showed that in the absence of these kinases, phosphorylation of SMN complexes at specific sites decreased sharply. This then causes the flash mobs in the nucleus to cease -- the Cajal bodies disintegrate. The finding is particularly interesting because the kinases identified not only regulate splicing, but also the translation of the gene transcripts edited in this way into proteins. These are therefore enzymes that are crucial for various steps in this vital process."

Comment: Mind-bending complexity, not designed by chance. All done by free-floating molecules which are free to make mistakes. The article shows one that might be helped in new therapy approaches. Our brains help undo some of the biological mistakes that occur, that God cannot prevent in the present system of life.