A series of proceeding tests showed that extra Gs facilitated damage to fold out from quadruplex and become easily accessible to repair enzymes.`
Recent findings published in the ACS Central Science reveal that every individual is carrying a little piece of extra DNA – much like ‘spare tires’ in a car for emergency situations. Researchers claim that an extra stretch of guanine bases present in our DNA act as a backup in the prevention of various forms of cancers from developing.
Why Extra Guanines
DNA is susceptible to various kinds of damage, which can make it unstable – the characteristic indication of cancer. While breathing or processing certain chemicals, a form of oxygen that can temporarily and severely damage DNA is sometimes formed, particularly targeting guanine bases (Gs). This mechanism, via which DNA damage occurs within our body, is known as ‘oxidative stress’. This damage must be immediately repaired for the body to remain cancer-free.
Surprisingly, it was observed that in a regulatory DNA structure known as ‘G-quadruplex’, the damaged Gs are not repaired through conventional repair mechanisms. Moreover, most people do not develop cancer, and the rate of the latter occurring is also not very high. In order to answer these questions, Cynthia Burrows and Susan Wallace along with colleagues conducted the present study.
Underhand Mechanism Discovered
After scanning the sequences of known human oncogenes (genes associated with cancer), the team found that many of them contained the four stretches of G’s necessary for the formation of the quadruplex. However, another fifth G-stretch was also present downstream. Researchers demonstrated that this extra stretch of guanines could function as ‘spare tires’ – coming into play to resolve the damage using typical repair machinery.
Furthermore, the research team exposed these quadruplex-forming sequences to oxidative stress in-vitro. A series of proceeding tests showed that the extra Gs facilitated the damage to fold out from the quadruplex and become easily accessible to repair enzymes.
It was also highlighted that these guanine quadruplexes were highly conservative in various genomes, which indicates that their presence could be specific ‘factory-installed’ safety feature in many different life forms.