Final answer:
MutS protein in methyl-directed mismatch repair serves to identify base-pair mismatches. It works together with MutL and MutH to excise the erroneous nucleotide and enables the correct base to be inserted, thus preserving the genetic sequence's accuracy. Mutations in mismatch repair enzymes can result in increased permanent mutations and disease risk.
Step-by-step explanation:
Function of MutS in Methyl-directed Mismatch Repair
The function of the MutS protein in methyl-directed mismatch repair is to recognize and bind to base-pair mismatches in the DNA double helix that can occur as a result of errors during DNA replication. In the process of methyl-directed mismatch repair, the DNA strands are differentiated by their methylation status; the parental DNA strand is methylated, and the newly synthesized daughter strand is not yet methylated. The MutS protein, along with MutL and MutH, facilitates the repair by identifying the mismatch. MutH then nicks the nonmethylated strand, allowing for exonucleolytic removal of a segment of the DNA including the incorrect base. This gap is later filled by DNA polymerase III and sealed by DNA ligase. This repair mechanism is critical to maintaining the integrity of the genetic information and preventing mutations which could lead to various diseases or disorders if the mismatch repair enzymes are themselves mutated.
As such, mutations in mismatch repair enzymes like MutS can lead to an increased risk of errors becoming permanent mutations in the genome, which has implications in the rise of certain types of cancers, most notably hereditary nonpolyposis colorectal cancer (Lynch syndrome).