Homologue frequencies for the Mu-like pangenome ORFs in the data bank. The ORFs in the pangenome of the P. aeruginosa Mu-like phages were analyzed by BLASTp to determine the number of homologues in the non-redundant NCBI database. The number of homologues identified for each ORF in viruses (red bars) or bacteria (grey bars) is plotted on the graph. The core ORFs (cORF), corresponding to those in PaMx73 genome, are labeled in black whereas the accessory ORFs (aORF) of different phage genomes (see Additional file 6) are labeled in blue and the corresponding bars shaded in green. The bars corresponding to ORFs encoding virion proteins identified by mass spectrometry in PaMx73 are shaded in purple. Three ORFs matching eukaryota homologues are indicated with asterisks (*) above the corresponding bars. No homologues were found in Archaea. Functions inferred for some ORFs are under the corresponding label. Functional modules are indicated by brackets above the histogram and the gene order in the graph is represented as in the phage genomes.