Analysis of the filamentous bacteriophage genomes integrated into Neisseria gonorrhoeae FA1090 chromosome

Bioinformatic analysis of the genome sequence of Neisseria gonorrhoeae revealed presence of four specific prophage islands. Based on the similarity with other DNA phage sequences they seem to belong to the filamentous ssDNA phages group. Phages belonging to this group are also present in the genome of Neisseria meningitidis. The nucleotide and amino acids sequence of NgoΦ6 and NgoΦ7 show similar genetic organization and high homology on DNA and amino acid level. The NgoΦ9 contains only part of the genomes of the NgoΦ6-8 prophages. Several functionally same genes of different origin are duplicated, with no homology to their counterparts in phages NgoΦ6, NgoΦ7 and NgoΦ9. The prophage sequences of nucleotides of NgoΦ6 and NgoΦ7 contain specific blocks of genes responsible for phage DNA replication and structural proteins. Comparative analysis at nucleotide and amino acid level suggests that these sequences can encode functionally active phages. The genetic organization of the NgoΦ6 suggests that it can serve as a prototype of filamentous phage of N. gonorrhoeae. Presence of the genomic ssDNA of these phages in the cultures of N. gonorrhoeae confirms this conclusion.