title: Novel histone H2A-like protein of escherichia coli.
abstract: A histone-like protein (H) from Escherichia coli has been purified to more than 98% homogeneity by using its capacity to inhibit DNA functions. H protein behaves as a dimer of 28,000-dalton subunits. The histone H2A-like properties of H protein are: (i) binding to DNA at a stoichiometry of 1 H protein dimer per 75 bases; (ii) abundance of about 30,000 molecules per cell, sufficient to bind about 20% of the chromosome; (iii) limiting digestion of double-stranded DNA by micrococcal nuclease; (iv) reannealing of complementary single-stranded DNA; (v) amino acid composition resembling that of eukaryotic histone H2A; (vi) neutralization of H protein by antibody specific for H2A; (vii) heat stability; and (viii) acid solubility. The capacity of H protein to bind DNA prevents its template or substrate functions n several reactions in vitro: DNA synthesis by several polymerases; transcription by RNA polymerase; DNA topoisomerase activity; and DNA-dependent ATP hydrolysis by rep protein, dnaB protein, or protein n'. Together with other histone-like proteins of E. coli, H protein may organize the E. coli chromosome into nucleosomes, such as in eukaryotic chromatin.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001426:Bacterial Proteins / Q000302:isolation & purification*; D002417:Cattle; D003429:Cross Reactions; D004269:DNA, Bacterial / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000032:analysis*; D005057:Eukaryotic Cells / Q000032:analysis; D006657:Histones / Q000276:immunology / Q000302:isolation & purification*; D008970:Molecular Weight; D009695:Nucleic Acid Renaturation
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D006657:Histones