Base mismatch-specific endonuclease activity in extracts from Saccharomyces cerevisiae
1Department of Biological Chemistry, University of Maryland, School of Medicine, Baltimore 21201.
Nucleic Acids Research
|September 11, 1991
Summary
Yeast extracts possess an endonuclease activity that nicks DNA at base mismatches. This MS-nicking occurs on a specific strand and may play a role in genetic recombination repair.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- DNA mismatches arise during replication and recombination.
- Efficient repair of DNA mismatches is crucial for genomic stability.
- Yeast Saccharomyces cerevisiae is a model organism for studying DNA repair mechanisms.
Purpose of the Study:
- To detect and characterize endonuclease activity on DNA base mismatches in yeast.
- To investigate the strand specificity and incision sites of this activity.
- To explore the potential role of this activity in DNA repair.
Main Methods:
- Enzyme assays using DNA substrates with defined base mismatches.
- Analysis of nicking efficiencies for all possible mismatch types.
- Mapping of nick positions and time-course studies.
Main Results:
- A novel endonuclease activity, termed MS-nicking, was identified in yeast extracts.
- Different base mismatches were nicked with varying efficiencies, with A/G and G/A being highly efficient.
- Nicking occurred on a specific DNA strand at phosphodiester bonds 5' to the mismatch, primarily at the fourth bond.
Conclusions:
- The MS-nicking activity exhibits distinct preferences for certain base mismatches.
- The strand-specific nicking suggests a role in directed DNA repair pathways.
- This activity is a potential candidate for involvement in mismatch repair during genetic recombination.
Related Concept Videos
01:36Mismatch Repair
Overview
01:54Base Excision Repair
One of the common DNA damages is the chemical alteration of single bases by alkylation, oxidation, or deamination. The altered bases cause mispairing and strand breakage during replication. This type of damage causes minimal change to the DNA double helix structure and can be repaired by the base excision repair (BER) pathways. BER corrects damaged DNA sequences by removing the damaged base and restoring the original base sequence using the complementary strand as a template.
The first step of...
The first step of...
01:02Long-patch Base Excision Repair
Since the discovery of the two BER pathways, there has been a debate about how a cell chooses one pathway over the other and the factors determining this selection. Numerous in vitro experiments have pointed out multiple determinants for the sub-pathway selection. These are:
01:11Restriction Enzymes
Restriction enzymes are bacterial enzymes used to cut DNA in a sequence-specific manner. To cleave DNA, they bind to specific palindromic sequences called restriction sites. Such palindromic DNA sequences or inverted repeats are commonly found in regions of functional significance, such as the origin of replication, gene operator sites, and regions containing transcription termination signals.
The host bacteria protect their own genomic DNA from these enzymes by methylating these sites. Some...
The host bacteria protect their own genomic DNA from these enzymes by methylating these sites. Some...
01:20Mismatch Repair
Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...