Characterization of the dsDNA prophage sequences in the genome of Neisseria gonorrhoeae and visualization of productive bacteriophage

Abstract

BackgroundBioinformatic analysis of the genome sequence of Neisseria gonorrhoeae revealed the presence of nine probable prophage islands. The distribution, conservation and function of many of these sequences, and their ability to produce bacteriophage particles are unknown.ResultsOur analysis of the genomic sequence of FA1090 identified five genomic regions (NgoΦ1 – 5) that are related to dsDNA lysogenic phage. The genetic content of the dsDNA prophage sequences were examined in detail and found to contain blocks of genes encoding for proteins homologous to proteins responsible for phage DNA replication, structural proteins and proteins responsible for phage assembly. The DNA sequences from NgoΦ1, NgoΦ2 and NgoΦ3 contain some significant regions of identity. A unique region of NgoΦ2 showed very high similarity with the Pseudomonas aeruginosa generalized transducing phage F116. Comparative analysis at the nucleotide and protein levels suggests that the sequences of NgoΦ1 and NgoΦ2 encode functionally active phages, while NgoΦ3, NgoΦ4 and NgoΦ5 encode incomplete genomes. Expression of the NgoΦ1 and NgoΦ2 repressors in Escherichia coli inhibit the growth of E. coli and the propagation of phage λ. The NgoΦ2 repressor was able to inhibit transcription of N. gonorrhoeae genes and Haemophilus influenzae HP1 phage promoters. The holin gene of NgoΦ1 (identical to that encoded by NgoΦ2), when expressed in E. coli, could serve as substitute for the phage λ s gene. We were able to detect the presence of the DNA derived from NgoΦ1 in the cultures of N. gonorrhoeae. Electron microscopy analysis of culture supernatants revealed the presence of multiple forms of bacteriophage particles.ConclusionThese data suggest that the genes similar to dsDNA lysogenic phage present in the gonococcus are generally conserved in this pathogen and that they are able to regulate the expression of other neisserial genes. Since phage particles were only present in culture supernatants after induction with mitomycin C, it indicates that the gonococcus also regulates the expression of bacteriophage genes.

DNA uptake sequences in Neisseria gonorrhoeae as intrinsic transcriptional terminators and markers of horizontal gene transfer

“…This spans a region containing lysogenic and filamentous prophage which have been previously outlined in N. gonorrhoeae strain FA1090 (Kawai et al, 2005,;Piekarowicz et al, 2006Piekarowicz et al, , 2007. Two gaps in DNA uptake sequence density within this region coincide with filamentous prophage NgoF6 (bases: 1 651 609-1 659 560) and NgoF9 (bases: 1 674 315-1 681 419).…”

Neisseria Prophage Repressor Implicated in Gonococcal Pathogenesis

“…Interestingly, the gene organization of Ngo⌽4 involves the Npr repressor characterized in this study and a putative integrase (NGNG_00463) resembling that of the R and F pyocin gene cluster present in P. aeruginosa. It is tempting to speculate that Ngo⌽4 plays a similar role in gonococcus (9).…”

Characterization of MDAΦ, a temperate filamentous bacteriophage of Neisseria meningitidis

“…In 2006, Piekarowicz and colleagues analysed the subtype Nf4 and showed the presence of a circular ssDNA form of the Nf4 phage in a N. gonorrhoeae phage preparation (Piekarowicz et al, 2006). In 2007, Piekarowicz and colleagues described N. gonorrhoeae prophage sequences that belong to the dsDNA tailed group of bacteriophage and which are biologically active (visualization of phage particles in phage preparation) (Piekarowicz et al, 2007). In 2014, the same team constructed a phagemid (pBS : : W6) derived from the N. gonorrhoeae filamentous bacteriophage NgoW6 [Nf4-G2(inv)] of the Nf4 group of Kawai and colleagues (Kawai et al, 2005), and showed that isolated phagemid particles contained ssDNA that could infect and replicate in a variety of Gram-negative bacteria (Piekarowicz et al, 2014).…”