The φEf11 lysis module includes a lysin/muramidase (PHIEF11_0026), and an amidase (PHIEF11_0028) transcribed in a rightward direction, and a LysM domain protein (PHIEF11_0030) divergently transcribed in a leftward direction. In addition, there is a holin protein (PHIEF11_0025) transcribed in a rightward direction and another (putative) membrane protein (PHIEF11_0029) divergently transcribed in a leftward direction. This complexity of lysis-related genes is not seen in the genome of other temperate selleck screening library Siphoviridae phages. The arrangement of the early genes that control the switch between the lytic and the lysogenic alternative life cycle pathways in phage φEf11 is similar to that found in most temperate

Siphoviridae phages: a repressor gene is divergently expressed from adjacent tandem cro and antirepressor genes. Within this module, between the repressor and the cro genes is a 159 bp noncoding sequence. It is likely that within this

span is an operator/promoter site (Fig. 2), controlling the expression of the adjacent repressor and cro genes. Finally, a virulent Myoviridae E. faecalis phage (φEF24C) has been described by Uchiyama et al. (2007). The genome of this virus has been sequenced and annotated (Uchiyama et al., 2008). The genome of this phage was found to be 142 072 bp, with a GC content of 35.7%, and predicted to encode 221 ORFs and five tRNA genes. Although this virus infects strains of the same species MRIP PKC inhibitor review (E. faecalis) as phage φEf11, with one exception, there is no similarity in genome size, arrangement or sequence.

The one common feature detected between the genomes of φEF24C and φEf11 is the sequence of the amidase gene (φEf11 PHIEF11_0028) of both viruses. blastp analysis reveals high sequence similarity (60.7% identity, p=1.9e−27) between these lytic enzymes of these two E. faecalis phages (Table 1). This may be due to the need for both of these phages to hydrolyze similar cell wall amide linkages in host E. faecalis cells, in order to be released following productive infection. However, it should also be noted that no such similarity was detected between the endolysin gene products (φEf11 PHIEF11_0026) of these viruses. Consequently, it must be concluded that, except for a degree of similarity in the method of achieving cell wall lysis of the host cell, these two viruses have developed alternative solutions in solving the problems of adsorbing to, replicating in, and lysing their host cell. To investigate whether other phage or prophage genomes exist that are similar to φEf11, we searched an NCBI blast-formatted protein database for top matching phage and prophage genomes. The database consisted of 579 NCBI RefSeq complete bacteriophage genomes, 1520 phage_finder-predicted (Fouts, 2006) prophages from 1102 complete RefSeq bacterial genomes, and 1463 phage_finder-predicted prophages from 1016 draft RefSeq bacterial genomes.