Nucleotide sequence of the exclusion-determining locus of IncI plasmid R144

The exclusion-determining locus (exc) of IncI plasmid R144 has been proposed to contain two overlapping genes. The nucleotide sequence of this locus, as presently determined, reveals an open reading frame with a coding capacity of 220 amino acids (aa) and with a promoter located upstream of the translation-initiation region. Consistent with the proposed overlapping gene arrangement, a second putative promoter was found within this coding region. Thus, a polypeptide identical to the 147 C-terminal aa of the larger polypeptide can be expressed from this second promoter. The 3'-noncoding region contains a sequence that is representative for a Rho-independent transcription terminator.