A strategically located serine residue is critical for the mutator activity of DNA polymerase IV from Escherichia coli

摘要: The Y-family DNA polymerase IV or PolIV (Escherichia coli) is the founding member of DinB family and known to play an important role in stress-induced mutagenesis. We have determined four crystal structures this enzyme its pre-catalytic state complex with substrate presenting possible template nucleotides that are paired corresponding incoming nucleotide triphosphates. In all structures, Ser42 residue active site forms interactions base moieties incipient Watson–Crick pair. This located close centre nascent pair towards minor groove. vitro vivo assays show fidelity increases drastically when Ser was mutated Ala. addition, structure mismatch A:C shows plays stabilizing dCTP a conformation compatible catalysis. Overall, structural, biochemical functional data presented here present at strategic location stabilize mismatches site, thus facilitate appearance transition transversion mutations.