Site-directed mutagenesis of the YCDTDS amino acid motif of the ø29 DNA polymerase

Abstract

The Bacillus subtilis phage Φ29 DNA polymerase, involved in protein-primed viral DNA repilcation, contains amino acid consensus sequences common to other α-like DNA polymerases. Using site-directed mutagenesis we have studied the functional significance of the most conserved C-terminal segment mainly represented by the YCDTDS motif. A series of single point mutants has been constructed and the corresponding proteins have been overproduced and characterized. Measurements, on crude fractions, of the activity of the mutant proteins in the formation of the protein p3-dAMP initiation complex and in an situ DNA polymerase assay, indicate that the YCDTDS domain is involved both in initiation and in elongation reactions.