Figure 2.

DNA polymerase activity of MucB. Gap-filling bypass replication was performed with MucB alone or in the presence of MucA′, RecA, and SSB using the gap-lesion plasmid GP21 as a substrate. Reactions were performed as described under Materials and Methods at 37°C for 10 min. When present, pol II was at a concentration of 100 nM. Reaction products were restricted, fractionated by urea-PAGE, and visualized by phosphorimaging. The DNA bands of 19, 29, and 47 nucleotides long represent the unextended primer, the replication product blocked at the abasic site, and the bypass product, respectively. M, size marker for the 47-mer bypass product.