Location of the serine residue involved in the linkage between the terminal protein and the DNA of phage phi 29.
B. subtilis phage phi 29 has a terminal protein, p3, covalently linked to the 5' ends of the DNA through a phosphodiester bond between a serine residue and 5'-dAMP. This protein acts as a primer in DNA replication by forming an initiation complex with the 5'-terminal nucleotide dAMP. The amino acid sequence of the terminal protein, deduced from the nucleotide sequence of gene 3, showed the presence of 18 serine residues in a total of 266 amino acids. In this paper we have identified the serine involved in the linkage with the DNA as the residue 232, located close to the C-terminus of the molecule. This result was obtained by amino acid analysis of the peptide that remains linked to the DNA after proteinase K digestion of the terminal protein-phi 29 DNA complex and automated Edman degradation of the corresponding [125I]-labeled tryptic peptide. Prediction of the secondary structure of the terminal protein suggested that the serine residue involved in the linkage with the DNA is placed in a beta-turn, probably located on the external part of the molecule, as indicated by hydropathic values.
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics*; D001435:Bacteriophages / Q000235:genetics*; D001665:Binding Sites; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D007457:Iodine Radioisotopes; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D012694:Serine; D014357:Trypsin; D014764:Viral Proteins / Q000378:metabolism*
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D014764:Viral Proteins; D012694:Serine; D014357:Trypsin