Extensive sequence analysis of 89K revealed several ORFs whose putative products show similarity to conjugation and mobilization proteins involved in conjugative DNA transfer (Fig. 1B) . On the 3′ half of the 89K island, a peptide encoded by 05SSU0913 showed similarities to various prokaryotic DNA relaxases that initiate conjugal transfer by strand-and site-specific cleavage at the transfer origin (oriT), such as the VirD2 component (accession number NP_059814.1) of the A. tumefaciens T4SS (36% aa identity) and the MobA relaxase (accession number AAA26445.1) of the broad host-range plasmid R1162 (39% aa identity). Peptide (05SSU0914), located adjacent to this relaxase, shared 36% aa identity to the accessory protein MobC (accession number AAA26444.1) of R1162, which is proposed to act as a molecular wedge, denaturing oriT strands and providing a single-stranded (ss) substrate for the relaxase (Zhang and Meyer, 1997) . Therefore, 05SSU0913 and 05SSU0914 were accordingly designated mobA89K and mobC89K respectively.