Maps of <i>exo-xis</i> regions and other genes of bacteriophages λ and Ф24_B analyzed in this work (accession numbers: GI:9626243 and GI:307604077 respectively).

<p>Dark arrows with continuous outside lines represent highly conserved genes and open reading frames (over 70% nucleotide as well as amino acid sequence identity). Dark arrows with punctuated outside lines represent highly conserved (above 70% sequence identity) open reading frames present in genomes of λ and 933W phages, available in the NCBI database but uncharacterized in annotations. The presence of <i>orf73</i> in the λ <i>exo-xis</i> region was indicated by <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108233#pone.0108233-Sergueev1" target="_blank">[48]</a>. Light arrows represent genes and open reading frames with low level of sequence identity (<38%). Note the high homology between λ and Ф24_B<i>exo-orf73</i> regions and low level of identity of other analyzed genes. Arrows indicate positions of promoters predicted with BPROM program. The localizations and −10 and −35 sequences of predicted promoters <i>p</i>_{1_λ} and <i>p</i>_{1_Φ24B} are exactly the same (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108233#pone-0108233-t003" target="_blank">Table 3</a>). Schematic steam-loop structures [•] indicate localizations of predicted transcription terminators, found on the basis of nucleotide seuquence analysis with ARNold software. The localizations and sequences of predicted terminators t₁ and t₂ are exactly the same in case of both phages λ and Ф24_B (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108233#pone-0108233-t004" target="_blank">Table 4</a>). Note that in the case of Ф24_B phage, some ORFs from the <i>exo-xis</i> region: <i>vb_24B_9c, vb_24B_8c, vb_24B_7c</i>, putative C4 zinc finger protein and <i>vb_24B_6c</i> are homologues of λ <i>orf60a, orf63, orf61, orf73</i> and gene <i>ea22</i> respectively. For clarity of this work, only the names of λ ORFs were used.