Protecting Genes, One Molecule At a Time
An international team of scientists have shown how cells prioritise the repair of genes containing potentially dangerous damage, at an unprecedented level of detail
The research, published in the journal Nature and involving academics from the University of Bristol, the Institut Jacques-Monod in France and Rockefeller University in the US, studied the action of individual molecules in order to understand how cellular repair pathways are triggered.
The genetic information that forms the "instruction booklet" for cells is encoded in the molecular building blocks of DNA, and can be damaged by mutagens such as ultraviolet light or tobacco smoke, as well as by normal "wear and tear" as the cells age. If left unrepaired, such damage can kill the cells or cause them to change their behaviour and perhaps cause disease.
Cells repair themselves by producing proteins
that detect damaged building blocks,
cut them out and replace them
with a new patch of DNA.
Most cells, including those both in bacteria and in humans, contain mechanisms to ensure that genes currently in use are repaired first.
The team, led by Dr Terence Strick of the Institut Jacques Monod, Paris, used single molecules of DNA stretched-out in a magnetic field to observe individual proteins at work in an active, damaged gene.
They found that more steps are needed to repair genetic damage than previously thought; and, that the length of time proteins reading the gene hesitate when they reach damage is critical to the successful handover to proteins that repair the gene.
Dr Nigel Savery from the University's School of Biochemistry, who led the Bristol-based part of the project, said: "Finding out how different parts of the genome are repaired at different rates, is critical to our understanding of processes as diverse as the generation of antibiotic resistance in bacteria, and the patterns of mutations that give rise to cancer.
Studying these processes at the level of single molecules, has allowed us to detect important steps - hidden when large numbers of molecules are studied together."
The work in Bristol was funded by the Biotechnology and Biological Research Council (BBSRC), UK.
"Initiation of transcription-coupled repair characterized at single-molecule resolution" is published online (ahead of print) in the journal Nature on 9 September 2012. doi: 10.1038/nature11430
Kévin Howan1, Abigail J. Smith2, Lars F. Westblade3, Nicolas Joly1, Wilfried Grange1, Sylvain Zorman1, Seth A. Darst3, Nigel J. Savery2 & Terence R. Strick1
1. Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Paris, France.
2. DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, England
3. The Rockefeller University, 1230 York Avenue, New York, USA
Original article: http://www.eurekalert.org/pub_releases/2012-09/uob-pgo090712.php