Staphylococcus aureus protease: a probe of exposed, non-basic histone sequences in nucleosomes
The digestion of histones in chicken erythrocyte nucleosome cores and chromatin by Staphylococcus aureus protease was examined. This protease cleaves specifically at acidic residues and prefers glu-X bonds under the conditions used. Only 1 of 24 glutamic and 2 of 13 aspartic acids among all four core histones are located in basic, amino-terminal tails, hence staph. protease is a highly specific probe of exposed non-basic sequences. Staph. protease readily degraded H1, H5, and H3; moderately degraded H2b, and only slightly degraded H2a and H4 in nucleosomes and nucleosome cores. Electrophoresis of core histone fragments from limited digests showed that most glutamic acids were inaccessible, but at least five sites in non-basic sequences were readily cleaved. Tentative assignments of these fragments based on comparisons with products from limited digests of pure histones suggested that most accessible sites in nucleosome cores occur in H3. The most probable sites of H3 cutting are glutamic acids at positions 51, 60, 73, 94, and 97. At least one site in H2b, probably the equivalent of glu-105 in the calf H2b sequence, was accessible. No sites in H2a and H4 appeared highly accessible. H5 was readily cleaved at a site near the amino-terminus. These data substantiate the other evidence that non-basic core histone sequences are located primarily in the nucleosome interior, but that H3 binds to the ends of core DNA and thereby is partly exposed as the upper and lower surfaces of the disk-shaped core.
- Research Organization:
- Florida State Univ., Tallahassee (USA)
- DOE Contract Number:
- AS05-78EV05888
- OSTI ID:
- 6252741
- Report Number(s):
- DOE/EV/05888-T2; ON: DE81030486
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HISTONES
ENZYMATIC HYDROLYSIS
STRUCTURAL CHEMICAL ANALYSIS
PEPTIDE HYDROLASES
ENZYME ACTIVITY
CHICKENS
DIGESTION
ERYTHROCYTES
NUCLEOSOMES
SPECIFICITY
STAPHYLOCOCCUS
ANIMALS
BACTERIA
BIOLOGICAL MATERIALS
BIRDS
BLOOD
BLOOD CELLS
BODY FLUIDS
CHEMICAL REACTIONS
CHROMATIN
DECOMPOSITION
ENZYMES
FOWL
HYDROLASES
HYDROLYSIS
LYSIS
MATERIALS
MICROORGANISMS
ORGANIC COMPOUNDS
PROTEINS
SOLVOLYSIS
VERTEBRATES
550200* - Biochemistry