Biological complexity: cellular DNA repair (Introduction)

by David Turell , Tuesday, March 24, 2020, 23:26 (1705 days ago) @ David Turell

A new study shows the complexity of this necessary process:

https://phys.org/news/2020-03-scientists-reveal-proteins-team-dna.html

"One of the main DNA repair processes is called homologous recombination (HR). This repairs a severe form of DNA damage where both strands of DNA are broken. A protein called Rad51 orchestrates HR, and Rad51 itself is supported by several 'helper' proteins.

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"Previous genetic studies have shown that there are two HR sub-pathways in yeast—one that depends on Swi5-Sfr1 and another that relies on molecules called Rad51 paralogs. To test whether it was this other HR pathway that was rescuing DNA repair, the team used yeast that lacked the Rad51 paralogs. The results were striking: in yeast with mutant Swi5-Sfr1 and no Rad51 paralogs, the DNA damage was much more severe. This suggests that the damaging effects of mutations to the Swi5-Sfr1 helper complex are suppressed by a second group of helper proteins.

"'Although these two groups of helper proteins were previously thought to function independently, our study shows that they actually work together to activate Rad51 in DNA repair," explains senior author Hiroshi Iwasaki, Professor at the Tokyo Institute of Technology. "The fundamental mechanisms of DNA repair are highly conserved from yeast to humans. Our new insight into DNA repair in yeast may serve as a template for understanding why DNA repair processes do not function properly in human disease.'"

Comment: Only a designer would see to it that more than one system was available to back up the vital repair process. Not by chance.