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Structural alteration from non-B to B-form could reflect DNase I hypersensitivity
1Molecular Biophysics Unit, Indian Institute of Science, Bangalore.
Journal of Biomolecular Structure & Dynamics
|April 1, 1989
Summary
DNase I enzyme preferentially cleaves active genes in the B-DNA form. Non-B DNA structures, like Z-DNA, resist DNase I digestion, indicating structural requirements for gene activation.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- DNase I enzyme preferentially cleaves active genes.
- This cleavage is linked to altered DNA conformations at hypersensitive sites.
- Understanding DNA structure is crucial for gene activation studies.
Purpose of the Study:
- To investigate the structural requirements for gene activation using DNase I.
- To compare the DNase I digestibility of DNA in B-form versus non-B (Z-form) conformations.
Main Methods:
- Studied DNase I digestibility of synthetic polynucleotides.
- Examined DNAse I action on Z-form DNA within supercoiled plasmids.
- Utilized DNase I footprinting in a protein-free system.
Main Results:
- B-form DNA showed significantly higher DNase I digestibility compared to Z-form DNA.
- Z-DNA structures exhibited marked resistance to DNase I digestion.
- Alternating purine-pyrimidine sequences in Z-conformation showed DNase I footprinting.
Conclusions:
- Altered DNA structures like Z-DNA are unfavorable substrates for DNase I.
- The B-form DNA, with a specific minor groove width, is a preferred DNase I substrate.
- DNA structures deviating from B-form but capable of reverting to it are potential DNase I targets in naked DNA.