Question

(Molecular Biology) Why does deamination of 5-methylcytosine lead to hot spots for spontaneous mutations?

Answer 1

Repairing systems that act on G-T mismatches have a bias on replace T with a C ..but this is not good as removal of U from G-U mismatches.Due to the above reason deamination of 5 methyl cytosine only leads to mutation rather than deamination of cytosine or correction.Possibility of mutation are always in CPG islands due to the random occurance of deaminated 5- methyl cytosine.Failure lies in our repairing systems actually.The greater probability of mutation are being avoiding by our DNA itself by replacing Uracil with Thymine.But the second most powerful mutation spot are these deaminated 5-methyl cytosine area.But onething is that because of the mutation only variation possible in population that ensures it's survival in world.At the same time this causes unnecessary human genetic disease in germline.