Mismatch Repair Mechanism Is One Of The Important DNA Repair Mechanism Which Recognizes And Replaces The Wrong Nucleotides. DNA Repair Is Important Since Its Failure Leads To Deadly Diseases Like Cancer. In This Presentation, You Will Learn About DNA Repair, Mismatch Repair, Proteins Involved In Prokaryotic And Eukaryotic MMR, Diagrams, Biological Importance Of MMR And References For Further Study.
2. DNA REPAIR
Set Of Processes Where A Cell Detects And Nullify Damages Occurred
In DNA.
Very Important Mechanism Since Its Failure Leads To Development Of
Severe Diseases.
Discovery “Tomas Lindahl, Paul Modrich And Aziz Sancar”.
They Received “Nobel Prize In Chemistry” In The Year “2015”.
Their Research Focused On “Molecular Mechanisms Of DNA Repair
Processes”.
3. DNA DAMAGE CAUSES
DNA Damages Are Caused By “Exposure To Several Endogenous And
Exogenous Agents”.
“Errors Occurred During DNA Processing Reactions” Also Causes
Damages In The DNA.
Endogenous Agents Reactive Oxygen, Nitrogen (Metabolites)
Exogenous Agents UV, Dioxin (Chemical And Physical Agents)
DNA Processing Reactions Replication, Recombination And Other
Biological Processes.
4. MISMATCH REPAIR
“Mismatch Repair (MMR)” Recognizes And Replaces The Wrong Bases
Arised Due To “Unwanted Insertion And Deletion” During The DNA
Processing Interactions.
Important Role In “Maintenance Of Genomic Stability” And “Cellular
Homeostasis”.
There Are “Two” Types.
Prokaryotic MMR.
Eukaryotic MMR.
6. PROKARYOTIC MMR
Mut S Important Protein Of MMR Initiates MMR Pathway By Recognizing
Non-specific Interactions 2 Functional Domains DNA Binding Domain And
ATPase Domain.
Mut L Mediator Protein B/W Mut S And Other Proteins Interacts With Mut S
And Initiates Endonuclease Activity Of Mut H Protein Acts As Recruiter Of
UVrD Protein.
Mut H Type II Restriction Endonuclease It Removes Mismatch DNAAt
Hemimethylated GATC Sites Mut H Capacity For Mismatch Removal Is
Stimulated By Mut S + Mut L + ATP Complex.
UVrD DNA Helicase II Enzyme It Unwinds The DNAAt Nick Point Made By
Mut H The Nick Point Is The Entry Point For Single Stranded DNA Binding
Protein And UVrD UVrD Takeup At Nickpoint Is Mediated By Protein-Protein
Interactions With Mut L.
7. EUKARYOTIC MMR
MSH MSH6 Protein Similar To Mut S Mut Sa (Mismatch Recognition)
And Mut Sb (Mismatch Repair). i.e. Insertion Deletion Loops (IDL).
MLH Similar To Mut L Responsible For Formation Of Heterodimer Three
Types Of Mut L Are Mostly Studied.
1. Mut La Supports Repair Initiated By Mut S Protein.
2. Mut Lb Functions Not Found.
3. Mut Lg Metabolic Recombination.
Accessory Proteins Responsible For Proper Functioning Of MMR Helps In
Recognition, Binding And Removal Of DNA Mismatch. i.e. Proliferating Cell
Nuclear Antigen (PCNA) And Exonuclease I (EXO I).