A new mechanism for the faithful replication of the damaged DNA

A new mechanism of protection of the cell against the damage of the DNA has been just highlighted in Medical & pharmacy journal.. It implements the DNA polymerase lambda, which, assisted by other replicative proteins, with the single capacity to recopy the DNA containing an oxydative lesion without making error of copying. This mechanism could thus play a key part in the protection of the organization against the appearance of cancers. This discovery, resulting from work undertaken by Giuseppe Villani, director of research in Inserm, the Department “Biology of the Cancer” of the Institute of Pharmacology and Structural Biology in Toulouse (IPBS-CNRS UMR 5089/University Paul Sabatier), in close cooperation with an Italian team and a Swiss team was published in the review Nature on May 31, 2007.
The DNA, molecule genetic carrier data, with the property to reproduce with the identical one, which makes it possible genetic information to be transmitted of a cell mother to the cells girls.
For the replication of their genome, all the organizations depend on enzymes able to recopy the DNA, the DNA polymerases. There are several families which have different functions in the cell. The DNA polymerases can bind to various proteinic factors, which control their activity, like their implication in the maintenance of the genome.
The DNA can be damaged by internal or external factors like drugs or radiations UV. Among these lesions, one finds oxidations of the DNA and particularly those which affect the Guanine base. The appearance of lesions on the DNA represents an obstacle with its replication. If they or are not badly repaired, they can lead to chromosomal rehandlings or changes which can lead to the appearance of cancers or other diseases by modifying the protein functions essential with the cellular metabolism. The replication of the damaged DNA is ensured by DNA specialized polymerases.
In this article it is shown that one of the 16 DNA known human polymerases, the DNA Lambda polymerase, is able to retort the mutagen lesion extremely 8-oxo-Guanine in a “faithful” way, thanks also to the coordinated action of two other proteins (PCNA and RP-A) necessary to the replication of the DNA
This discovery makes it possible to assign a new role with the action of the DNA Lambda Polymerase and highlights the fact that proteins implied in the replication of the DNA play also a part essential in the protection of the cell against the oxydative damage. The whole of these results thus suggests the existence of a new mechanism able to support cellular survival while reducing the noxious consequences of a change.


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