Circular dichroic and sedimentation studies of phosphorylated H1 from Chinese hamster cells

Journal Article · Tue Mar 20 04:00:00 EST 1979 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00573a002· OSTI ID:6472148

D'Anna, J A; Strniste, G F; Gurley, L R

Phosphorylated histone H1 (H1/sub p) was isolated from Chinese hamster (line CHO) cell cultures syncghronously enriched in metaphase cells, and unphosphorylated H1 (H1/sub 0/) was isolated from cells arrested in G/sub 1/ by isoleucine deprivation. Circular dichroic measurements of CHO H1/sub p/, CHO H1/sub 0/, and calf thymus H1 indicate that (a) the cell-cycle-dependent phosphorylations of H1/sub p/ do not alter the sensitivity of CHO H1 to undergo salt-induced folding in solution; (b) the net secondary structure of folded H1 is not affected by H1 phosphorylation; (c) the presence of divalent cations (which might bind to the phosphates of H1/sub p/) does not alter H1 folding or the folded conformation of H1/sub p/; and (d) the net secondary structure of folded CHO H1 is the same as that of calf thymus H1 and involves about 15% of the H1 residues. Sedimentation measurements of phosphorylated or unphosphorylated H1 provide no evidence of H1:H1 interactions in solution. Finally, H1:DNA complexes of CHO H1/sub 0/ or H1/sub p/ and PM2 DNA were prepared by direct mixing. Sedimentation boundary measurements as a function of sodium chloride concentration show that both H1/sub 0/ and H1/sub p/ induce formation of a 140 +- 20S component and of large heterogeneous aggregates (greater than or equal to 1500 S). While the salt concentrations required to induce these sedimenting species are similar for both H1/sub 0/ and H1/sub p/, the circular dichroic spectra of H1/sub 0/:DNA and H1/sub p/:DNA in the aggregated complexes (120 mM NaCl) are different from one another. These studies indicate that the cell-cycle-dependent phosphorylations of histone H1 have little effect upon H1 conformation, H1:H1 interactions, or ability of H1 to induce aggregation of DNA in H1:DNA complexes as a function of sodium chloride concentration. Nevertheless, circular dichroic spectra of aggregated H1:DNA complexes indicate that H1 phosphorylation does alter the interaction of H1 with DNA.

• Research Organization: Univ of California, Los Alamos, NM
• OSTI ID: 6472148
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 18:6; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ANIMAL CELLS
ANIMALS
BIOCHEMICAL REACTION KINETICS
CELL CULTURES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
DATA
DATA FORMS
DICHROISM
DNA
EXPERIMENTAL DATA
GRAPHS
HALIDES
HALOGEN COMPOUNDS
HAMSTERS
HISTONES
INFORMATION
ISOLATED VALUES
KINETICS
MAMMALS
MOLECULAR STRUCTURE
NUCLEIC ACIDS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOSPHORYLATION
PROTEINS
REACTION KINETICS
RODENTS
SEDIMENTATION
SODIUM CHLORIDES
SODIUM COMPOUNDS
SPECTRA
VERTEBRATES