The sequence of the leading region of the resistance plasmid R1.

The region of the resistance plasmid Rl which is transferred first during conjugation (leading region) has been sequenced. It is shown together with the oriT region of this plasmid (1) in the figure. The putative strand-specific cleavage site selected in analogy to the site which was experimentally determined for the F plasmid (2), is designated by the word 'nick . Two open reading frames of opposite orientation were detected in the leading region. The one designated gene 19 is oriented opposite to all other known tra genes of Rl (3, 4, 5). It codes for a 19.29 kDa protein (pl9). The other gene, termed gene 32, codes for a 31.5 kDa protein (p32). Both proteins could be expressed (Graus, Schroller and Hogenauer, unpublished). Arrows designate the translation^ starts of pl9 and p32. Nucleotides 1925 to 2130 were taken from a previous publication (1).