Nucleotide sequence of the Borrelia burgdorferi dnaN gene encoding the β subunit of DNA polymerase III

The order of genes in the dnaA region of Eubacteria is highly conserved with the consensus being rnpA-rpmH-dnaA-dnaN-recF-gyrB. From a Borrelia burgdorferi 212 library of chromosomally-enriched DNA we isolated homologues of the closely linked genes dnaA, dnaN, gyrB, gyrA, rpmH and rnpA which are located at the centre of the linear chromosome. We demonstrated that the Spirochaete B. burgdorferi is unique among the Eubacteria as the gene order in the dnaA region is mpA-rpmH-dnaN-dnaA-gyrB-gyrA. DNA polymerase III, which is encoded by dnaN, is a complex, multichain ATP-independent enzyme which is responsible for most of the DNA synthesis in bacteria. The beta chain is required for initiation of replication by the enzyme. We have sequenced the B. burgdorferi 212 dnaN gene and the dnaN-rpmH intergenic region.