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Sequence-specific complex formation of DNA and a eukaryotic sequence-specific endonuclease, SceI
K Kawasaki1, M Takahashi, T Ando
1Laboratory of Microbiology, Riken (Institute of Physical and Chemical Research), Wako-shi, Japan.
European Journal of Biochemistry
|December 5, 1991
Summary
Endonuclease SceI (Endo.SceI) binds DNA specifically, independent of cleavage. This enzyme is a heterodimer composed of 75-kDa and 50-kDa subunits, with implications for DNA repair and gene editing research.
Area of Science:
- Molecular Biology
- Enzymology
- Genetics
Background:
- Endonuclease SceI (Endo.SceI) is a eukaryotic enzyme known for sequence-specific DNA double-strand breaks.
- Previous studies identified a consensus sequence rather than a common sequence at cleavage sites, suggesting complex recognition mechanisms.
Purpose of the Study:
- To investigate the sequence-specific DNA binding of Endo.SceI independent of its cutting activity.
- To characterize the composition and properties of the DNA-binding entity of Endo.SceI.
Main Methods:
- Gel mobility shift assays were employed to study Endo.SceI binding to double-stranded DNA.
- DNA re-isolation from protein-DNA complexes was performed to assess cleavage.
- Analysis of protein subunits involved in DNA binding was conducted.
Main Results:
- Endo.SceI exhibits sequence-specific binding to a 41-bp double-stranded DNA containing its cleavage site, without cleaving the DNA.
- The DNA-binding activity resides in a heterodimer of 75-kDa and 50-kDa polypeptides.
- Binding is specific to double-stranded DNA and shows higher affinity for the consensus sequence; Mg2+ is not required but stimulates binding.
Conclusions:
- Endo.SceI functions as a heterodimer of 75-kDa and 50-kDa subunits.
- The enzyme possesses sequence-specific DNA binding capabilities distinct from its endonuclease activity.
- These findings provide insights into the mechanism of DNA recognition by Endo.SceI.