Genome complexity: grouping genes for better function (Introduction)

by David Turell , Monday, September 16, 2019, 17:36 (1678 days ago) @ David Turell

A new study finds this is true across DNA's:

https://phys.org/news/2019-09-manual-genome-groups-genes-convenience.html

"Every living organism's cell has a complete copy of DNA, which is condensed tightly in chromosomes. Every time the cell needs to perform a function, it activates genes that open or close different regions in the DNA. Like following an instruction manual with consecutive pages, it's easier to activate two genes that are closer together to complete a function.

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"'If genes for a specific biological process are placed near each other in the chromosome, they can co-regulate each other in a more coordinated and effective manner," says Gabaldón.
The scientists developed an algorithm capable of identifying genes near each other in genomes of different species according to their evolutionary history, i.e. looking for whether they were conserved clusters in different species of fungi, independently of the function they had. They predicted more than 11000 families of grouped genes in the genome. Of the 300 genomes analysed, they found that a third were part of a conserved group.

"'Natural selection means some genes are near each other for functional relevance. The way they're organized isn't random chance—they have been selected because it makes regulating genes easier. We've found that it's pretty common, and that it affects an important proportion of the genome," says Gabaldón. "The selective forces favor the conformations of genes that allow a smaller investment in energy and improved regulatory processes," he adds.

"Previous studies of gene groups linked to secondary metabolism observed that they had a switch, a type of transcription factor, to turn them on and off. Other observations also found that these gene groups passed from one species to another in block, known as horizontal transfer, though no one knew why.

"The CRG scientists have now provided evidence that horizontal transfer may be less common than previously thought, and their most recent findings don't represent what the genome does as a whole. They saw that a cluster made up of the same groups of genes appeared independently twice, in parallel distant lineages.

"Surely, the groups of genes carry out a specific function. "When you need something at a precise moment, it's when you most need it to be co-regulated. A general function, which is active most of the time, doesn't need such precise regulation," says Marina Marcet-Houben, first author of the study."

Comment: Ease of function is a purposeful design mechanism, and fits my thought about pre-programming by design.