6). PFGI-1 does not encode a Rep protein, and it is not clear whether it replicates by a theta-type or strand displacement mechanism, although the latter has been suggested for pKLC102 [30]. Like some conjugative plasmids, PFGI-1 carries homologues of the stress-inducible genes umuC (PFL_4692) and umuD (PFL_4691), which encode a putative lesion bypass DNA polymerase and a related accessory protein,

respectively. Such genes may be involved in plasmid DNA repair and umuDC-mediated mutagenesis, which could allow plasmids to adapt more quickly to new bacterial hosts [41]. PFGI-1 also contains a cluster of 10 genes, pilLNOPQRSTUVM (PFL_4675 through PFL_4683) (Fig. 6), that spans over 10 kb and click here closely resembles part of the pil region from the self-transmissible E. coli plasmid R64 [42]. In E. coli, these genes are involved in production of thin flexible sex pili A-769662 concentration required for mating and transfer of R64 in liquid media. The similarity between the pil clusters of R64 and PFGI-1 suggests that the latter encode mating pili rather than type IV pili involved in bacterial twitching motility, adherence to host cells, biofilm formation and phage sensitivity [43]. P. fluorescens Pf-5 has the capaCity to produce type IV pili,

and the corresponding biosynthetic genes are located in at least three clusters found outside of PFGI-1. The PFGI-1 www.selleckchem.com/products/Vorinostat-saha.html pil cluster contains genes for pilin protein PilS (PFL_4680), prepilin peptidase PilU (PFL_4681), outer membrane protein PilN (PFL_4676), nucleotide binding protein PilQ (PFL_4678), integral membrane protein PilR (PFL_4679), and pilus adhesin PilV (PFL_4682). Unlike R64, PFGI-1 does not include a shufflon Olopatadine region that determines recipient specifiCity in liquid matings via generation of different adhesin types [42, 44]. Finally, PFGI-1 carries genes

encoding proteins that may be involved in conjugal DNA transfer. PFL_4696 and PFL_4706 encode for TraG-like coupling proteins that may function as membrane-associated NTPases, which during conjugation would mediate transport of DNA covalently linked to a putative relaxase protein (the product of PFL_4751). Recent studies have demonstrated that ICEs are a major component of a flexible gene pool of different lineages of Gram-negative Proteobacteria [45–47]. Metabolically versatile members of the Pseudomonadaceae are no exception, with ICEs having been identified among strains of P. aeruginosa [29–32], P. syringae [36, 48], and P. fluorescens [49]. Comparison of PFGI-1 with islands from other Pseudomonas spp. reveals at least six highly conserved gene clusters (Fig. 7).