Linked Life Data

2160975

Source:http://linkedlifedata.com/resource/pubmed/id/2160975

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
16
pubmed:dateCreated
1990-7-2
pubmed:abstractText
Chromatin with nucleosomes spaced at 180-base pair intervals can be formed in vitro on circular DNA molecules using a Xenopus oocyte S-150 extract, but the ability to form a periodic chromatin structure is lost upon fractionation of this extract. To identify factors other than the known ones involved in chromatin assembly, we have first depleted the extract by incubating it in batch with charged resins, and we have subsequently reconstituted it with purified fractions. Studies performed with the fractionated components indicate that formation of periodically spaced nucleosomes on the relaxed, closed circular DNA proceeds in two steps and does not require DNA topoisomerases. In a first step, histones H3/H4 are transferred from the endogenous H3/H4-N1 complex to the DNA, forming a nascent chromatin structure. This structure can then be rapidly complemented in a subsequent and independent step with a stoichiometric amount of histone H2A/H2B dimers. Under these experimental conditions, excess histone H2A/H2B dimers inhibit DNA supercoiling and nucleosome formation. We describe the purification of a factor from the Xenopus oocyte S-150 which permits DNA supercoiling and nucleosome formation under conditions of excess histone H2A/H2B. The activity purifies as a complex of five nonacidic polypeptides with apparent molecular masses ranging between 56 and 62 kDa. This factor prevents the binding of excess histone H2A/H2B to the DNA, and it can also remove excess histone H2A/H2B already bound to the DNA, thus ensuring that stoichiometric amounts of all four nucleosomal histones associate with the DNA.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
265
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9357-65
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Purification and mechanism of action of a nucleosome assembly factor from Xenopus oocytes.
pubmed:affiliation
Department of Biology, University of Rochester, New York 14627.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't