site specific single strand endonuclease from the eukaryote Chlamydomonas

We have found a unique deoxyribonuclease in extracts of the eukaryotic green alga Chlamydomonas. When incubated with viral DNA from adenovirus-2, this enzyme produces discrete fragments that form bands upon electrophoresis in an agarose gel. Site specificity of the enzymatic cleavage, examined by id...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1977-07, Vol.74 (7), p.2687-2691
Main Authors: Burton, W.G, Roberts, R.J, Myers, P.A, Sager, R
Format: Article
Language:English
Subjects:
Adenoviruses
Algae
Base Sequence
Biochemistry
Chlamydomonas - enzymology
Deoxyribonucleases - metabolism
DNA
DNA, Single-Stranded - metabolism
DNA, Viral - metabolism
Electrophoresis
Endonucleases - isolation & purification
Endonucleases - metabolism
Enzymes
Eukaryotic cells
Gels
Molecular Weight
Molecules
Nucleotides
Polynucleotides
Thymidine - metabolism
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Description
Summary:We have found a unique deoxyribonuclease in extracts of the eukaryotic green alga Chlamydomonas. When incubated with viral DNA from adenovirus-2, this enzyme produces discrete fragments that form bands upon electrophoresis in an agarose gel. Site specificity of the enzymatic cleavage, examined by identifying the 5′-terminal nucleotides in cleaved adenovirus-2 DNA and by studies with synthetic polynucleotides of defined sequence, indicates that the initial endonucleolytic cleavage occurs at a site containing a deoxythymidine residue. Electron microscopy of cleaved adenovirus-2 DNA revealed single-strand segments within duplex DNA. We propose that the enzyme acts by making initial site-specific single-strand incisions, followed by subsequent excision on the same strand, producing a gapped duplex molecule; and that double-strand scissions result from limited occurrence of overlapping single-strand gaps on complementary strands.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.74.7.2687