tokens: Pseudomonas aeruginosa RdgC adds a unique member to the repertoire of toroidal DNA - binding proteins ( 26 ) such as D . radiodurans RecR ( 27 ) and DNA polymerase processivity factors , including the beta subunit of E . coli DNA polymerase III ( 28 ) , gp45 of T4 DNA polymerase ( 29 ) and PCNA of eukaryotic DNA polymerase delta ( 30 , 31 ) ( Figure 5 ) .