Protein collisions derail DNA replication
3 Mar 2011 by Evoluted New Media
DNA replication is riskier than originally thought say researchers at the University of Nottingham who liken DNA to a bi-directional rail track with two types of train.
DNA replication is riskier than originally thought say researchers at the University of Nottingham who liken DNA to a bi-directional rail track with two types of train.
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Collisions between proteins during DNA replication can cause catastrophic damage |
Collisions between these types of train – the fast train or DNA replisome, and the slow train, RNA polymerase – can be catastrophic and is one of the reasons why areas of DNA that are used a lot are particularly prone to damage.
“As it travels, the big train – the DNA replisome – is responsible for copying the DNA e.g. when a cell is preparing to divide. And the small train – the RNA polymerase – makes its journey to deal with the expression of genes contained within the DNA sequence,” said lead researcher Panos Soultanas.
Until now, scientists thought only head on collisions between DNA replisome and RNA polymerase could lead to serious damage. However, this new research shows that collisions between DNA replisome and RNA polymerase running in the same directions can be just as dangerous.
“We thought that if the fast and slow protein-trains meet going in the same direction also on the track then the faster DNA replication train just slows down and follows behind the slower gene expression train until it has finished its job,” said Soultanas. “This isn’t the case at all and in fact they do collide quite often causing what, in this analogy, we could only describe as a major derailment.”
Restart replication proteins help the DNA replisome get back onto its DNA track, ensuring replication can continue, but it can increase the risk of mistakes in the copying process, particularly if they are malfunctioning. This can lead to cancer developing.
“We are now realising that when there are a lot of slow moving trains close together on the track, the fast moving train is faced with a huge obstacle and any failure to safely negotiate these areas could easily result in significant errors,” Soultanas said. “Replication restart mechanisms are of vital importance to ensure accurate copying of genetic material!”
