When proof-reading/editing goes wrong in a cell

Syed Akbar
Hyderabad:  Scientists at the city-based Centre for Cellular and Molecular  Biology have unravelled the mystery that goes behind "proof reading", "editing", and  "translation" of genetic information, giving a new insight into the process that causes  diseases including neurodegeneration.
They have found out that diseases are caused when the mechanism of "proof reading" or "editing" the genetic code in the cells goes haywire and additional wrong information is added during the process.
"To put it in layman's language, it is like a copy editor not only failing to rectify the existing errors, but also adding new errors to the copy. The scientific view held thus far is that diseases are caused when the mechanism fails to rectify the errors. We have now found that it not only fails to rectify the errors, but also adds more errors to the genetic process involved," said senior scientist Dr Rajan Shankarnarayanan.
The body has inherent internal checks to maintain the body functioning in good condition. Important mechanisms, which scientists call, "proof reading" or "editing", and "translation", take place inside the cells to produce proteins. "Proof reading" or "editing" is a natural process of correcting the errors during the formation of proteins, while "translation" involves the synthesis of protein.
"Our study helps in finding out the secret behind the diseases, those linked to genetics and neurodegeneration. It has given a new insight into the mechanism of discrimination during proof reading in translation," he pointed out.
Every individual possesses DNA, which carries genetic information. This genetic code is passed on to the RNA through a process called transcription. RNA uses this information to prepare proteins by a method known as translation. Binding proteins in their right place is done by what scientists called "proof reading", which also carries out the correction. Nature has programmed that this process is done in an accurate manner.
"A high rate of accuracy is involved in the entire process. As any compromise in the whole process leads to formation of defective proteins and thus causes a number of diseases. If the protein is wrong it will bind to a wrong amino acid, the building blocks of genetic information. Proof reading ensures that this wrong protein is eliminated. But sometimes, it fails to eliminate the wrong protein, and also adds more errors to it," Dr 
Sankarnarayanan said.
Proof-reading mechanisms play a crucial role in the faithful flowof information as dictated by the genetic code. Proof-readingoccurs at two important steps in the cell, one during DNA replication and another during translation, and is essential for the transfer of genetic information.
The study opens up an interesting question on the fundamental mechanism of discrimination of cognate amino acids at the proof-reading step.