The transfer region of IncI1 plasmid R64: similarities between R64 tra and Legionella icm/dot genes

• Published in: Molecular microbiology Vol. 35; no. 6; pp. 1348 - 1359
• Main Authors: Komano, Teruya, Yoshida, Tetsu, Narahara, Koji, Furuya, Nobuhisa
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.03.2000
• Subjects: Amino Acid Sequence; Bacterial Proteins - genetics; DNA Transposable Elements; DNA-Binding Proteins - genetics; DNA-Directed RNA Polymerases - genetics; DNA-Directed RNA Polymerases - metabolism; dot gene; Escherichia coli Proteins; Gene Transfer Techniques; Genes, Bacterial - genetics; icm gene; Legionella - genetics; Legionella pneumophila; Molecular Sequence Data; nik gene; nuc gene; Open Reading Frames; Plasmids - genetics; Sequence Homology, Amino Acid; traE-Y gene; trb gene; Viral Proteins
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1046/j.1365-2958.2000.01769.x

The entire nucleotide sequence of the transfer region of IncI1 plasmid R64 was determined together with previously reported sequences. Twenty‐two transfer genes, traE–Y and nuc, were newly identified in the present study. The protein products of 17 genes were detected by maxicell experiments or by the T7 RNA polymerase expression system. Mutagenesis experiments indicated that 16 genes were indispensable for R64 transfer both in liquid and on surfaces. In summary, the R64 transfer region located within an ≈ 54 kb DNA segment was shown to encode the most complex transfer system so far studied. It contains at least 49 genes and may produce 58 different proteins as a result of shufflon DNA rearrangement and overlapping genes. Among the 49 genes, 23 tra, trb and nik genes have been shown to be indispensable for R64 conjugal transfer in liquid and on surfaces. Twelve additional pil genes are required only for liquid matings. The amino acid sequences of 10 R64 tra/trb products share similarity with those of the icm/dot products of Legionella pneumophila that are responsible for its virulence, suggesting that the R64 transfer and L. pneumophila icm/dot systems have evolved from a common ancestral genetic system.