title: Bacteriophage phi X174 A protein cleaves single-stranded DNA and binds to it covalently through a tyrosyl-dAMP phosphodiester bond.
abstract: The phi X174 A protein cleaves single-stranded DNA and binds covalently to the 5'-phosphorylated end. To determine the nature of the covalent linkage and the amino acid involved, we used the A protein to cleave DNA synthesized in vitro with [alpha-32P]dATP to form the complex of A protein covalently linked to single-stranded DNA. The complex was then digested with DNase I, and the 32P-labeled A protein was isolated by electrophoresis on polyacrylamide gels. The isolated complex was treated extensively with trypsin, and the released peptide-oligonucleotide complexes were incubated with formic acid and diphenylamine (Burton reaction). The Burton reaction caused a transfer of the labeled phosphate from dAMP to the peptide. The labeled phosphopeptides were isolated and hydrolyzed, revealing a linkage of the phosphate to a tyrosine. These results indicate that the A protein cleaves single-stranded DNA and binds covalently to the 5'-phosphorylated terminus by a tyrosyl-dAMP phosphodiester bond.
authors.forename: S
authors.initials: S
authors.lastname: Sanhueza
authors.forename: S
authors.initials: S
authors.lastname: Eisenberg
mesh_terms: D010584:Bacteriophage phi X 174 / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism*; D003838:Deoxyadenine Nucleotides / Q000378:metabolism; D010766:Phosphorylation; D014443:Tyrosine / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D003838:Deoxyadenine Nucleotides; D014764:Viral Proteins; D014443:Tyrosine; C012873:2'-deoxy-5'-adenosine monophosphate