Characterization of a Bacillus subtilis 64-kDa DNA Polymerase X Potentially Involved in DNA Repair

Bacillus subtilis gene yshC encodes a 64-kDa family X DNA polymerase (Polx(Bs)), which contains all the critical residues involved in DNA and nucleotide binding as well as those responsible for catalysis of DNA polymerization, conserved in most family X members. Biochemical analyses of the purified enzyme indicate that PolX(Bs) is a monomeric and strictly template-directed DNA polymerase, preferentially acting on DNA structures containing gaps from one to a few nucleotides and bearing a phosphate group at the 5' end of the downstream DNA. The fact that PolX(Bs) is able to conduct filling of a single-nucleotide gap, allowing further sealing of the resulting nick by a DNA lipase, points to a putative role in base excision repair during the B. subtilis life cycle. (C) 2008 Elsevier Ltd. All rights reserved.