Structural alteration from non-B to B-form could reflect DNase I hypersensitivity

Brahmachari, Samir K. ; Ramesh, N. (1989) Structural alteration from non-B to B-form could reflect DNase I hypersensitivity Journal of Biomolecular Structure and Dynamics, 6 (5). pp. 899-906. ISSN 0739-1102

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Preferential cleavage of active genes by DNase I has been correlated with a structurally altered conformation of DNA at the hypersensitive site in chromatin. To have a better understanding of the structural requirements for gene activation as probed by DNase I action, digestability by DNase I of synthetic polynucleotides having the ability to adopt B and non-B conformation (like Z-form) was studied which indicated a marked higher digestability of the B-form of DNA Left handed Z form present within a natural sequence in supercoiled plasmid also showed marked resistance towards DNase I digestion. We showthat alternating purine-pyrimidine sequences adopting Z-conformation exhibit DNase I foot printing even in a protein free system. The logical deductions from the results indicate that 1) altered structure like Z-DNA is not a favourable substrate for DNase I, 2) both the ends of the alternating purine-pyrimidine insert showed hypersensitivity, 3) B-form with a minor groove of 12–13 Å is a more favourable substrate for DNase I than an altered structure, 4) any structure of DNA deviating largely from B form with a capacity to flip over to the B-form are potential targets for the DNase I enzymic probes in naked DNA.

Item Type:Article
Source:Copyright of this article belongs to Taylor and Francis Group.
ID Code:96162
Deposited On:19 Dec 2012 11:45
Last Modified:19 Dec 2012 11:45

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