Recent genome analyses suggest that integrative and conjugative elements (ICEs) are widespread in bacterial genomes and therefore play an essential role in horizontal transfer. However, only a few of these elements are precisely characterized and correctly delineated within sequenced bacterial genomes. Even though previous analysis showed the presence of ICEs in some species of Streptococci, th...

Legionella pneumophila is able to survive inside phagocytic cells by an internalization route that bypasses fusion of the nascent phagosome with the endocytic pathway to allow formation of a replicative phagosome. The dot/icm genes, a major virulence system of L. pneumophila, encode a type IVB secretion system that is required for intracellular growth. One Dot protein, DotL, has sequence simila...

The symbiotic, nitrogen-fixing bacterium Sinorhizobium meliloti has been widely studied due to its ability to improve crop yields through direct interactions with leguminous plants. S. meliloti AK21 is a wild type strain that forms nodules on Medicago plants in saline and drought conditions in the Aral Sea Region. The aim of this work was to establish the genetic similarities and differences be...

Plasmid conjugation systems are composed of two components, the DNA transfer and replication system, or Dtr, and the mating pair formation system, or Mpf. During conjugal transfer an essential factor, called the coupling protein, is thought to interface the Dtr, in the form of the relaxosome, with the Mpf, in the form of the mating bridge. These proteins, such as TraG from the IncP1 plasmid RP4...

CORRECTION In the publication of this article [1], the molecule weight of GPR30 in figures was incorrectly, this should have been 55 kDa, and not 38 kDa. This has now been included in this erratum.

We created plasmids for use in insertion-duplication mutagenesis (IDM) of Neisseria gonorrhoeae. This mutagenesis method has the advantage that it requires only a single cloning step prior to transformation into gonococci. Chromosomal DNA cloned into the plasmid directs insertion into the chromosome at the site of homology by a single-crossover (Campbell-type) recombination event. Two of the ve...

Pilus biogenesis and substrate transport by type IV secretion systems require energy, which is provided by three molecular motors localized at the base of the secretion channel. One of these motors, VirB11, belongs to the superfamily of traffic ATPases, which includes members of the type II secretion system and the type IV pilus and archaeal flagellar assembly apparatus. Here, we report the fun...

The conjugative transfer region 1 (Tra1) of the IncHI1 plasmid R27 was subjected to DNA sequence analysis, mutagenesis, genetic complementation, and an H-pilus-specific phage assay. Analysis of the nucleotide sequence indicated that the Tra1 region contains genes coding for mating pair formation (Mpf) and DNA transfer replication (Dtr) and a coupling protein. Insertional disruptions of 9 of the...

The mobilization region of plasmid CloDF13 was localized to a 3.6 kb DNA segment that was analysed by transposon mutagenesis and DNA sequencing. Analysis of the DNA sequence allowed us to identify two mobilization genes and the CloDF13 origin of conjugative transfer (oriT), which was localized to a 661 bp segment at one end of the mobilization (Mob) region. Thus, the overall organization was or...

TraG-like proteins are essential components of type IV secretion systems. During secretion, TraG is thought to translocate defined substrates through the inner cell membrane. The energy for this transport is presumably delivered by its potential nucleotide hydrolase (NTPase) activity. TraG of conjugative plasmid RP4 is a membrane-anchored oligomer that binds RP4 relaxase and DNA. TrwB (R388) is...