A Variant Protein from φ29 Replication Gene, Gene 1, Did Not Form Homo-Polymer Due to a Single Amino Acid Substitution Near the Carboxyl Terminus

For study of the self-association of the product of φ29 gene 1, one variant which has a substitution at the 71st amino acid was used. By glycerol gradient sedimentation, the product of wild-type gene 1 existed both as large aggregate and oligomer, whereas the variant was detected as a single peak of monomer size. According to experiments using His-tagged proteins and Ni-NTA magnetic beads, the variant made only a little self-associated complex. From these results, a site essential for self-association was suggested to exist close to the carboxyl terminus of the product of φ29 gene 1.