In addition to p03, efaB5 and the vanB -surrounding phage element, these included p01 (n = 5), PAI (n = 7), p04 (n = 21), p06 (n = 1) and pTEF1 and pTEF2 (n = 5) (Additional file 2). In addition, a ten-gene cluster (EF3217 to -27) with significant GC skew compared to the genome-average (31.6 and 37.4%, respectively), was found to be significantly more frequent in strains belonging to CC2 than in non-CC2 strains. The deviation in GC content CH5424802 suggests that this genetic element
may also be of foreign origin. This notion was further supported by the sequence similarities of several of the genes with known phage-related transcriptional regulators (EF3221, EF3223 and EF3227). Moreover, EF3221 to -22 showed high degree of identity (>85%) to EfmE980_2492 to -93 of the newly sequenced Enterococcus faecium E980 . EfmE980_2492 holds a domain characteristic of the aspartate aminotransferase superfamily of pyridoxal phosphate-dependent enzymes. Interestingly, EF3217 encodes a putative helicase, while EF3218 encodes a putative MutT protein, both with implications
in DNA repair [34, 35]. A potential role of these genes in protection against oxidative DNA damage induced in the hospital environment and during infection is plausible. To further investigate the distribution Ispinesib in vivo of EF3217 to -27 in E. faecalis, 44 strains were screened by PCR (Additional file 3): 10 CC2-strains held all ten genes, while 19 strains including two CC2-strains were
devoid of the entire element. Moreover, 2 strains contained EF3225 only, 3 strains contained EF3217 to -18, while 8 strains, including OG1RF, contained EF3226 only. The two latter patterns of presence and divergence of EF3217 to -27 were also obtained with BLASTN analysis of TX0104 and OG1RF, respectively, corroborating that these are indeed genuine polymorphisms in this locus. Notably, in the OG1RF genome five more genes (OG1RF_0214 to -18) are also located between the homologs of EF3216 and EF3230 , suggesting this locus may SGC-CBP30 clinical trial represent ADAMTS5 a hot spot for insertions. Partial sequencing across the junction between EF3216 and EF3230 suggested that several of the non-CC2 strains carry genes homologous to OG1RF_0214 to -18 in this locus (results not shown). Mobile DNA constitutes a substantial fraction of the E. faecalis V583 genome and transfer of MGEs and transposons thus plays an important role in the evolution of E. faecalis genomes . The large pool of mobile elements also represents an abundant source of pseudogenes, as indel events occurring within coding regions often render genes nonfunctional. To verify the expression of the CC2-enriched genes, we correlated the list of enriched genes with data from two transcriptional analyses performed in our laboratory with the same array as used in the CGH experiment described in present study ( and Solheim, unpublished work).