Interaction of DNA with DNA‐Binding Proteins The Characterization of Protein HD from Escherichia coli and Its Nucleic Acid Complexes

: DNA-binding protein HD with a monomer molecular weight of 9000 was isolated from Escherichia coli cells. The protein occurs as a tetramer under native conditions and binds to single and double-stranded DNA and also to RNA. DNA complexed with protein HD is a poor template for DNA synthesis by E. coli polymerase I, II or III holoenzyme. Exonuclease III is hindered in degrading HD-protein-covered double-stranded DNA, whereas exonuclease I can digest complexed single-stranded DNA. Transcription is liqhtly stimulated in the presence of protein HD.