For example, it has been suggested that the PAPS reductase gene, which functions in the assimilatory sulfate reduction pathway, could serve as a fitness factor under conditions of iron limitation for the lysogens that harbor prophages encoding this enzyme [42]. PAPS reductase genes were identified in three members of the Siphoviridae-like group, ϕE125, ϕ644-2 and PI-E264-3 (Fig. 4), and in the Myoviridae-like B subgroup member PI-E264-2. The PAPS reductase moron incorporated between two highly conserved phage genes (Fig. 4)
at a location that appears to be an insertion hotspot, since the other members of this group contain different morons (Fig. 4 and rectangles in Fig. 3). Other morons appear to be associated with enhanced host or bacteriophage competitiveness. For example, morons within the Myoviridae, see more Undefined-1, Undefined-2, and Siphoviridae encode for the production of toxins that inhibit the growth of competing bacterial strains (bacteriocins) and/or their associated translocation mechanisms (Table 2). Other morons could prevent infection of their host by other phage, these include morons that encode for site-specific endonucleases, DNA methylases, restriction-modification systems, phage abortive infection resistance, and phage-growth
limiting genes. Although we could not confirm that GI3 from K96243 contains morons (since LCB analysis was limited to those PIs that formed clusters), two separate buy I-BET151 reverse-transcriptase (RT) modules are encoded in this PI. Many phage-encoded RT described to date also function in phage resistance by directly targeting other phage DNA. Lastly, some of the morons encode for proteins associated with bacterial virulence (Table 2). Two different morons encode patatin-like phospholipases (PTP), which in P. aeruginosa can act as cytotoxins necessary for virulence in amoeba and contribute to lung injury in
a mouse model [18, 49, 50]. Moreover, a prophage-encoded phosholipase in group A Streptococcus also appears to enhance virulence and its expression results in more severe disease [49]. Selleckchem C59 Two other morons encode for a proteophosphoglycan and a lytic transglycosylase, both of which have been associated with virulence in other MK0683 nmr pathogens [51]. Thus, some phages in Burkholderia spp. might also be implicated in enhanced virulence. Moron and phage genes are differentially expressed in Bp DD503 We performed transcription analysis using RNAseq to determine to what extent phage genes and morons are expressed in ϕ1026b. The results demonstrate that most phage genes are normally not expressed in rich laboratory growth conditions (Table 3), and allowed us to determine at least one putative repressor that maintains such regulation. For ϕ1026b, the candidate repressor gene (phi1026bp79) had a very high expression value which was 4-times higher than any of the phage structural or replication genes, (Table 3).