A novel DNA-binding protein associated with DNA polymerase-alpha in pea stimulates polymerase activity on infrequently primed templates

A 42 kDa DNA-binding protein is associated with DNA polymerase-a-primase in pea (Pisum sativum). In a previous publication it was shown that the prote in has strong preference for ds-ss junctions in DNA, including the cohesive termini generated by restriction endonucleases. In this paper it is shown that when the DNA-binding protein is added back to polymerase-primase, the protein stimulates the activity of the polymerase. The stimulation is parti cularly marked when M13 DNA, primed with a single sequencing primer or prim ed with oligoribonucleotides by the polymerase's associated primase activit y, is used as a template. The stimulation of polymerase activity is not cau sed by an increase in processivity. These data lead to the suggestion that the 42 kDa DNA-binding protein is a primer-recognition protein.