Chromatin structural changes in synchronized cells blocked in early S phase by sequential use of isoleucine deprivation and hydroxyurea blockade

Journal Article · Sat Jan 01 04:00:00 EST 1983 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00293a027· OSTI ID:6603516

D'Anna, J A; Prentice, D A

The authors have investigated the loss of histone H1 from chromatin and the structure of chromatin from Chinese hamster (line CHO) cells blocked in early S phase by sequential use of isoleucine deprivation G/sub 1/ block and 1 mM hydroxyurea (HU) blockade. Measurements of H1 content in the cell and histone turnover indicate that H1 is lost from the cell and that there is negligible replacement synthesis of H1 during the period of the S-phase block. As H1 is lost, chromatin appears to undergo structural change. After 10 h of HU block, the new deoxyribonucleic acid (DNA) and a portion of the old DNA have measured nucleosome repeat lengths (37/sup 0/C digestion). By 24 h of HU block, nearly all of the chromatin has assumed a pseudoimmature conformation in which the nucleosome cores appear to be more closely packed along the DNA chain, but the new DNA is slightly more resistant than old DNA to attack by micrococcal nuclease. Electrophoretic analysis of nucleoprotein particles produced by micrococcal nuclease digestion of nuclei indicates that: the distribution of mononucleosome species changes during Hu block and some mononucleosome species appear to be enriched in normally minor proteins which may determine the electrophoretic mobility of the nucleoprotein particles in agarose-acrylamide gels. The results raise the possibility that: during the early stages of replication (or prior to the passage of the replication fork), H1 is dissociated from initiated replicons and H1 does not reassociate in a concerted fashion with the H1-depleted chromatin until the replication fork has passed and, perhaps, a substantial portion of the replicon has been replicated.

• Research Organization: Los Alamos National Lab., NM
• OSTI ID: 6603516
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 22:24; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMAL CELLS
ANIMALS
BIOSYNTHESIS
CARBOXYLIC ACIDS
CHANNELING
CHROMATIN
DNA
DNA REPLICATION
ENZYME ACTIVITY
ENZYMES
ESTERASES
HAMSTERS
HISTONES
HYDROLASES
MAMMALS
MORPHOLOGICAL CHANGES
NUCLEASES
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
NUCLEOSOMES
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHODIESTERASES
PROTEINS
RODENTS
SYNTHESIS
ULTRASTRUCTURAL CHANGES
VERTEBRATES