Genome complexity: enzyme repairs broken DNA (Introduction)

by David Turell , Monday, September 05, 2016, 22:15 (2788 days ago) @ David Turell

This research pinpoints how damaged areas of DNA are discovered, marked for repair. The agent is an enzyme which are large complex molecules:-http://phys.org/news/2016-09-scientists-super-enzyme-dna.html-"New research funded by the MRC and Cancer Research UK, led by the laboratories of Professor Keith Caldecott and Professor Laurence Pearl at the University of Sussex's Genome Damage and Stability Centre, has identified how the enzyme PARP3, short for poly(ADP-ribose) polymerase 3, recognises and signals the presence of broken DNA strands. -"Research has shown that the PARP3 enzyme is involved in the DNA repair process and helps to maintain the integrity of the genetic code, but until now the precise DNA repair activation mechanism triggered by the enzyme was unclear.-***-"When the PARP3 enzyme locates a specific site of DNA damage, it 'marks' the damaged DNA with a molecular signal.-"This signal is created via a chemical change, involving the addition of a molecule called 'ADP-ribose' to the DNA. The DNA is packaged up in a complex called 'chromatin' which contains proteins; the team found that the PARP3 enzyme adds the 'ADP-ribose' molecule to one of these proteins - 'histone H2B'.-"By marking the precise site of damage the enzyme flags the problem up to specialised DNA repair enzymes that will move in to repair the damage, protecting the cell from potentially dangerous DNA breaks.-***-"PARP3 is one of a superfamily of enzymes that are targeted by PARP inhibitor drugs, a new class drugs used to treat hereditary cancer, including ovarian and breast cancer. Knowledge of how the PARP3 enzyme activates DNA repair will also contribute to improving the understanding, and targeting, of PARP inhibitor drugs."-Comment: Note these are automatic molecular reactions which must occur quickly to protect the integrity of DNA and prevent bad mutations. The key issue is that these enzymes have specific lock and key areas which can lock to the problem areas and initiate the repair. How did evolution find such large specific molecules to do this job early in the history of life, without which life could not have safely continued? See this link in Wikipedia to understand how complex these enzymes are in structure. Follow the links in the structure paragraph to see diagrams of the enormous structure:-https://en.wikipedia.org/wiki/PARP3 -Not by chance.