Phylogenetic tree of the replication initiation protein (Rep) of IncU-family plasmids. The analysis was based on 27 sequences (from fully sequenced plasmids) and 217 amino acid positions. The unrooted tree was constructed using the neighbor-joining algorithm with Kimura corrected distances, and statistical support for the internal nodes was determined by 1000 bootstrap replicates. Values of >50% are shown. Accession numbers of the protein sequences used for the phylogenetic analysis are given in parentheses.