Genome complexity: a new DNA repair mechanism found (Introduction)

by David Turell , Sunday, April 07, 2019, 05:07 (2058 days ago) @ Balance_Maintained

Another way of repairing DNA is found:

https://phys.org/news/2019-04-unjamming-genome-dna-gene-regulatory.html

"RNA polymerase II (RNAPII)—the enzyme that produces RNA from a DNA template—can become stuck due to damage to the DNA template, and these jams must be cleared to restore gene expression and normal cell function. New research shows that the master regulatory complex, "Ccr4-Not," performs this task, associating with RNAPII during the transcription of RNA from DNA and marking RNAPII for degradation when it becomes stuck, allowing the DNA to be repaired and normal cell function to resume.

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"'The Ccr4-Not complex is involved in nearly every step of this process from start to finish. Our new research shows that this complex has an additional function that helps maintain normal cellular function when something goes wrong during transcription."

"During the transcription of RNA from DNA, RNAPII—itself a large complex made up of multiple protein subunits—travels along the strand of DNA reading the ATCG sequence and producing a complementary strand of RNA. If the RNAPII encounters DNA damage, which can be caused by UV radiation and other sources, it can become stuck and prevent trailing polymerases from completing transcription of the gene, similar to how a stalled car prevents traffic behind it from flowing. If this jam cannot be cleared, multiple RNAPIIs transcribing the same gene can start to pile up in a sort of traffic jam preventing the DNA from being repaired and hampering cell function.

"'The clearing of stuck RNAPII is an essential process for normal cell function," said Reese.
"'Defects in this pathway have been associated with a number of diseases and human syndromes, such as Cockayne syndrome—a neurodegenerative disorder that results in growth failure, neurological developmental defects, and sensitivity to UV light.

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"'Previous studies had implicated Ccr4-Not in helping cells cope with DNA damage," said Reese. "Mutating members of the Ccr4-Not complex makes cells more sensitive to agents that damage the genome, but because Ccr4-Not is involved in so many aspects of gene regulation it wasn't clear until now what its precise role was. The fact that Ccr4-Not recruited the destruction machinery to RNAPII was a surprisi'ng result, and suggests it acts as a tow truck to remove traffic jams throughout the genome. "

Comment: Same point as before. Once DNA is in control the repair mechanism must also be in control or life does not survive. Development of all parts at once implies only design can accomplish this.