Bacteriophage phi X174 A protein cleaves single-stranded DNA and binds to it covalently through a tyrosyl-dAMP phosphodiester bond

S Sanhueza, S Eisenberg
1985 Journal of Virology  
The +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 [a-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
more » ... 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 4AMP 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.
doi:10.1128/jvi.53.2.695-697.1985 fatcat:bxgla4qjhfdh3imebgcn4wt2nu