Structure and nucleotide sequence of the region encoding the mobilization proteins of plasmid CloDF13.

Mobilization of the non-conjugative plasmid CloDF13 requires both gene products of a conjugative plasmid and CloDF13-encoded information. About 30% of the CloDF13 genome is involved in plasmid transfer. The CloDF13 mobilization region comprises sequences acting in cis (bom, basis of mobilization) as well as protein-coding sequences (mob). Here we present the nucleotide sequence of the genes encoding the CloDF13 mobilization proteins. We confirmed the previous genetic data that the plasmid CloDF13 encodes two proteins involved in plasmid mobilization. The information for these proteins, designated B and C having Mrs of 57,890 and 15,870, respectively, is located within one operon directed by a promoter at 94% of the CloDF13 genome. The gene encoding the smaller protein is located distally within this operon. Transcription proceeds counter-clockwise and is terminated beyond gene C, although it can not be excluded that attenuation of the transcript occurs in the intergenic region. The role of the CloDF13 mobilization proteins in plasmid transfer will be discussed.