A nucleosome-free region in SV40 minichromosomes

Jakobovits, Edward B.; Bratosin, Susan; Aloni, Yosef

doi:10.1038/285263a0

Cited by 243 publications

(120 citation statements)

References 30 publications

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“…(16,17). Secondly, electron micrographs of SV40 chromatin (18,19) show the same kind of zigzag structure which has been found in systematic electron microscope studies on cellular chromatin, and which has been attributed to the presence of HI on the side of the nucleosome at the entry and exit points of the DNA (20 (20)). …”

Section: Is There a Linkage Number Problem?mentioning

confidence: 74%

The helical periodicity of DNA on the nucleosome

Klug¹,

Lutter²

1981

Nucl Acids Res

165

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Section: Is There a Linkage Number Problem?mentioning

confidence: 74%

The helical periodicity of DNA on the nucleosome

Klug¹,

Lutter²

1981

Nucl Acids Res

165

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“…Thus Simian Virus 40 DNA, which in infected cells forms nucleosomes (7), was found to possess a nuclease-sensitive region localized around the origin of replication and containing a promotor region of about 300-400 pairs in length (7). This region appears to be devoid of nucleosomes as shown by electron microscopy (8)(9)(10). In vitro experiments have shown that using purified histones H2A, H2B, H3 and H4, the reconstitution of nucleosomes is possible with polydeoxynucleotides composed of alternating purine- (11,12,13).…”

Section: Introductionmentioning

confidence: 99%

Conformation of DNA in chromatin reconstituted from poly [d(A-T)] and the core histones

Brahms¹,

Brahmachari²,

Angelier³

et al. 1981

Nucl Acids Res

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Present results provide direct evidence of the nature of a conformational change in DNA when nucleosomes are formed from core histones and poly fd(A-T)]. First, we have found some features which have characteristic aspects of the A like conformation of DNA. Thus, an increased contribution due to a sugar conformation close to C3'-endo puckering is detected in the Raman spectra. In addition, the circular dichroism (C.D.) spectra of reconstituted chromatin with poly PI(A-T)j exhibits an increased intensity at about 262 nm.A second feature acquired by poly rd(A-T)l in nucleosome formation from core histones is related to the presence of a negative band at about 280 nm in the C.D. spectra. The nature of this change is correlated with a DNA conformation characterized by a decreased number of base pairs per turn (28,29). This indicates that these two features of reconstituted nucleosomes reflect the presence of two types of DNA conformations, which overall form is of the B type (22,36).

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“…A short segment of the viral genome (ca. 400 base pairs [bp] extending from the SV40 origin of replication in the late direction) is hypersensitive to endonuclease cleavage (33,(38)(39)(40) and appears, in the electron microscope, as a region which is free of nucleosomes (19,32). Recently, more detailed studies have shown that, within the nuclease-sensitive site, there are subregions with differential sensitivity to DNase 1 (7,8,31,32).…”

mentioning

confidence: 99%

Barriers to nuclease Bal31 digestion across specific sites in simian virus 40 chromatin.

Scott¹,

Walter²,

Cryer³

1984

Mol. Cell. Biol.

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A portion of the nucleoprotein containing viral DNA extracted from cells infected by simian virus (SV40) is preferentially cleaved by endonucleases in a region of the genome encompassing the origin of replication and early and late promoters. To explore this nuclease-sensitive structure, we cleaved SV40 chromatin molecules with restriction enzymes and digested the exposed termini with nuclease Bal3l. Digestion proceeded only a short distance in the late direction from the MspI site, but some molecules were degraded 400 to 500 base pairs in the early direction. By comparison, BglI-cleaved chromatin was digested for only a short distance in the early direction, but some molecules were degraded 400 to 450 base pairs in the late direction. These barriers to Bal3l digestion (bracketing the BglI and the MspI sites) define the borders of the same open region in SV40 chromatin that is preferentially digested by DNase I and other endonucleases. In a portion of the SV40 chromatin, Bal3l could not digest through the nuclease-sensitive region and reached barriers after digesting only 50 to 100 base pairs from one end or the other. Chromatin molecules that contain barriers in the BglI to MspI region are physically distinct from molecules that are open in this region as evidenced by partial separation of the two populations on sucrose density gradients.Viral nucleoprotein complex extracted from cells infected by simian virus 40 (SV40) resembles cellular chromatin (1,10,15,27). A short segment of the viral genome (ca. 400 base pairs [bp] extending from the SV40 origin of replication in the late direction) is hypersensitive to endonuclease cleavage (33,(38)(39)(40) and appears, in the electron microscope, as a region which is free of nucleosomes (19,32). Recently, more detailed studies have shown that, within the nuclease-sensitive site, there are subregions with differential sensitivity to DNase 1 (7,8,31,32). Presumably, these features reflect the structural details of the nucleoprotein within this region.Nuclease-hypersensitive sites usually occur over regions which contain genetic signals. Such a chromatin structure over a eucaryotic promoter may be a necessary (but not sufficient) condition for transcription from that promoter (6,12,43). In addition, hypersensitive sites have been reported which are probably not related to promoter function (3,22,28). SV40-infected cells provide a good opportunity to investigate the details of the nuclease-sensitive chromatin structure, since SV40 chromatin is present in high concentration by comparison with other genes and can easily be separated from bulk cellular chromatin.We have developed a new approach for probing nucleoprotein structure which should be applicable to the study of chromatin structure in other minichromosomes. SV40 is cleaved with a restriction enzyme which cuts at a unique position, and the exposed termini are digested with Bal3l, an exonuclease which can degrade from either 3' or 5' ends. MATERIALS AND METHODSGrowth of cells and virus infections. African green monk...

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A nucleosome-free region in SV40 minichromosomes

Cited by 243 publications

References 30 publications

The helical periodicity of DNA on the nucleosome

The helical periodicity of DNA on the nucleosome

Conformation of DNA in chromatin reconstituted from poly [d(A-T)] and the core histones

Barriers to nuclease Bal31 digestion across specific sites in simian virus 40 chromatin.

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