Deletion Mutants Which Affect The Nuclease-Sensitive Site In Simian Virus 40 Chromatin

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Cellular and Molecular Biology


A short segment of simian virus 40 (SV40) chromatin on the late side of the origin of replication is hypersensitive to nuclease cleavage. The role of DNA sequence information in this nuclease-sensitive feature was examined by constructing deletion mutations in this region. Deletions were introduced into the inserted segment of in(Or)-1411 (a viable, partially-duplicated variant of SV40). The nuclease-sensitivity of the inserted segment in the viral chromatin was compared to that of the unaltered sequence in their normal location in the genome. Extended deletions essentially abolished nuclease-sensitivity within the inserted segment. Shorter deletions at separate locations retained the nuclease-sensitive feature and nuclease-susceptibility was reduced to different extents by the mutations. Similar results were obtained when nuclease-sensitivity was assayed by BglI restriction enzyme cleavage of the viral chromatin. These results suggest that more than one cis-acting genetic element within this segment contributes to the organization of the nuclease-sensitive feature.


Biology, Genetics

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