Identification and characterization of a native Dichelobacter nodosus plasmid, pDN1

The gram-negative anaerobe Dichelobacter nodosus is the primary causative a gent of ovine footrot, a mixed bacterial infection of the hoof. We report h ere the characterization of a novel native plasmid, pDN1, from D. nodosus. Sequence analysis has revealed that pDN1 has a high degree of similarity to broad-host-range plasmids belonging, or related, to Escherichia coli incom patibility group Q. However, in contrast to these plasmids, pDN1 encodes no antibiotic resistance determinants, lacks genes E and F, and hence is smal ler than all previously reported IncQ plasmids. In addition, pDN1 belongs t o a different incompatibility group than the IncQ plasmids to which it is r elated. However, pDN1 does contain the replication and mobilization genes t hat are responsible for the extremely broad host range characteristic of In cQ plasmids, and derivatives of pDN1 replicate in E. coli. In addition, the mobilization determinants of pDN1 are functional, since derivatives of pDN 1 are mobilized by the IncP alpha plasmid RP4 in E. coli. (C) 2000 Academic Press.