Question

How might repair enzymes know when there has been a mismatch during proofreading and repair of DNA?

Please go into depth, as I already understand that polymerase and other proofreading mechanisms are ABLE to identify mismatched base pairs. What I would like explained is how. How does it recognize mismatched base pairs? How does methylation play a role as well as nicks in eukaryotic DNA strands?

Answer 1

The mismatched pairs alter the stability of the strands.They cause disortion in the DNA strands and specific proteins like MutS are involve in identification of these disturbances along with polymerase enzyme by proofreading and causes the mismatch repair.

DNA methylation is important in gene expression and is important for various regulatory processes.

For example the methylation of cytosine to form 5-methyl cytosine does keep the same sequence of DNA and if converted to thymine by demination may result in mismatched pair.

Nicks are involved in the liberating the torsional strain to reduce the damage to DNA.