Detection of Covalent DNA-Protein Complexes: The Adenovirus DNA-Terminal Protein Complex and HeLa DNA-Protein Complexes

Abstract

There are now clear examples of proteins covalently joined to nucleic acids. Covalent nucleic-acid-protein complexes occur as structural components of the chromosomes of DNA-containing viruses (Ortin et al. 1971; Robinson et al. 1973; Arnberg and Arwert 1976; Ito et al. 1976) and RNA-containing viruses (Flanegan et al. 1977; Nomoto et al. 1977; Sangar et al. 1977). In the case of adenovirus (Ad), a 55,000-dalton protein (Rekosh et al. 1977; R. J. Roberts, pers. comm.), called terminal protein, is covalently linked to each end of the linear, double-stranded (DS) DNA molecule. Several observations suggest that terminal protein is joined to the 5’ ends of Ad DNA: (1) Viral DNA is hydrolyzed by 3’-specific Escherichia coli exonuclease III (Green et al. 1967; Younghusband and Bellett 1971; Carusi 1977; Stillman et al. 1977), but not by the 5’-specific exonuclease of bacteriophage γ (Carusi 1977; R. J. Roberts, pers. comm.). (2) The 5’ ends...