Mismatch Repair

Mismatch repair

fixes errors in replication

• Incorrect base pairs

• Insertions and Deletions in repetitive sequences

Mismatch repair proteins bind to, bacteria vs eukaryotes

locations of mismatches and direct the removal of part of the newly-synthesized strand

• This pathway is conserved in bacteria and eukaryotes

• Bacterial proteins MutS and MutL have homologs MSH and MLH in eukaryotes

• Mutations in MSH and MLH are associated with several human cancers

Mismatch repair proteins bind to, what do they do

locations of mismatches and direct the removal of part of the newly-synthesized strand

Mismatch repair pathways

This pathway is conserved in bacteria and eukaryotes

Mismatch repair proteins types

bacterial proteins MutS and MutL have homologs MSH and MLH in eukaryotes

Mutations in MSH and MLH are associated with several human cancers

Mismatch repair process

1. MSH binds the site of the mismatch

2. MLH cuts the backbone of the newly-synthesized strand

3. A piece of the nascent strand is removed

4. DNA polymerase fills the gap

5. Ligase seals the nick

Mismatch repair process step 1

MSH binds the site of the mismatch

Mismatch repair process step 2

MLH cuts the backbone of the newly-synthesized strand

Mismatch repair process step 3

A piece of the nascent strand is removed

Mismatch repair process step 4

DNA polymerase fills the gap

Mismatch repair process step 5

Ligase seals the nick

The mechanism of mismatch repair in eukaryotes

is not fully understood

RPA = single-stranded binding protein

PCNA= sliding clamp used in replication

RPA

single-stranded binding protein

PCNA

sliding clamp used in replication

Important proteins

MSH, MLH, exonuclease, DNA pol, ligase