The DNA repair mechanisms. Dissemination 87th
The mechanisms of self-healing of the alterations of the DNA is a vital importance subject in understanding of an inner working of cells, if we consider that DNA consists of the material where all functions of living things are codified, including instructions for the formation of organs. This genetic structure is a chemical construction of complex of millions of compounds arranged in a accurate result, the alteration involves disfunction (disease) or death of the cells. Therefore study of self-healing mechanisms continue an issue of vital importance.
From 1967 Thomas Lindahl has conducted numerous studies to explain why the many chemical undesirable changes which are daily suffering human DNA do not convert, directly, in alteration pathology as the cancer.This researcher concluded that there should be existing a natural self-healing mechanism of these damages and finally discovered a mechanism called "base excision repair" consisting of detecting, cutting and replacing of the damaged base otherwise it connects two enzymes called DNA glycosylases and AP endonuclease. Both are synthesized by the ribosoms of cells own self-healing thanks to the DNA gene itself. Thomas Lindahl showed that this process occurs in both procariotas(Saccharomyces) and eucariotas cells, therefore a very primitive mechanism.
Other errors in the DNA structure occur during replication in the same cell division. Paul Modrich, has studied this phenomenon like Thomas Lindahl and discovered that there should be a mechanism for self-healing. The mechanism discovered by Paul Modrich called "mismatch repair system" consisting of the activity of endonuclease mutagenic (M, Lm, S and U) synthesized by the ribosomes of the cells own self-healing thanks to the DNA gene itself. Paul Modrich has demonstrated that this process occurs in both procariotas (circular DNA E. coli) and eucarioticas cells, therefore a very primitive self-healing mechanism.
Another DNA alterations may occur by the action of physical (UV) or chemical agents. Aziz Sancar, as Lindahl and Modrich, considered that it should be a self-healing mechanism that would avoid the physical or chemical assault, to become permanent alterations of DNA. This mechanism has been defined as "nucleotide excision repair" and involves the sequential activity of the DNA polymerase and DNA ligase synthesized by ribosomes, the cells themselves, thanks to the self-healing DNA gene itself. Aziz Sancar has also shown that this process occurs in both procariotas and eucarioticas cells, although there are some differences between the two types of cells. To summarize this blog disclosure the researchers Lindahl, Sancar and Modrich have been awarded the 2015 Nobel in Chemistry for his research on the mechanisms of self-healing DNA that led to the discovery of the activity of 5 enzymes and DNA endonucleases glycolasas AP endonucleases Mut, DNA polymerase and DNA ligase (proteins synthesized on ribosomes to receive an order from the cell nucleus through the RNA.)