Related Experiment Videos
Sequence specific cleavage of DNA by micrococcal nuclease
Nucleic Acids Research
|June 25, 1981
Summary
Micrococcal nuclease preferentially cleaves DNA at specific sequences like 5'CATA and 5'CTA, with GC-rich regions enhancing attack. Contrary to prior beliefs, AT-rich regions are unexpectedly spared, complicating chromatin structure studies.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Micrococcal nuclease is a commonly used enzyme for DNA analysis.
- Previous studies suggested it preferentially cleaves AT-rich DNA regions.
Purpose of the Study:
- To investigate the DNA sequence specificity of micrococcal nuclease during partial digestion.
- To clarify the enzyme's cleavage patterns and their implications for chromatin studies.
Main Methods:
- Partial DNA digestion using micrococcal nuclease.
- Analysis of cleavage sites on mouse satellite DNA and pBR22 plasmid fragments.
Main Results:
- Micrococcal nuclease preferentially attacks 5'CATA and 5'CTA sequences.
- GC-rich flanking sequences increase initial cleavage probability.
- Unexpectedly, long AT-rich stretches are resistant to cleavage.
- Exonucleolytic degradation occurs at newly generated DNA termini.
Conclusions:
- The cleavage specificity of micrococcal nuclease is sequence-dependent, not solely AT-content dependent.
- Findings contradict previous assumptions about micrococcal nuclease activity on AT-rich DNA.
- This specificity poses challenges for using micrococcal nuclease to study nucleoprotein structure in chromatin.