title: Purification and characterization of a protein from Escherichia coli which forms complexes with superhelical and single-stranded DNAs.
abstract: From the cells of an Escherichia coli K-12 strain, a 22,000-dalton protein which has an affinity for the superhelical DNA molecule was purified to apparent homogeneity by monitoring the DNA-binding activity using the filter binding assay. In the sedimentation analysis of the DNA-protein complex, the protein has an affinity for the superhelical or single-stranded DNA molecule but neither for the open-circular nor for the linear DNA molecule. The amino acid composition of the protein resembled those of the other prokaryotic histone-like proteins and also to eukaryotic histones H2A and H2B. The protein precipitated upon heating, which is in contrast to the heat-stable feature of the other histone-like proteins. Furthermore, DNA and RNA syntheses in vitro were not affected by the presence of the protein. In view of these characteristics, this protein may play a role in maintaining the bacterial nucleoid structure.
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification* / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D004265:DNA Helicases / Q000302:isolation & purification* / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D004265:DNA Helicases