Abstract
Bacteriophages (or phages) play major roles in the evolution of bacterial pathogens via horizontal gene transfer. Multiple phages are often integrated in a host chromosome as prophages, not only carrying various novel virulence-related genetic determinants into host bacteria but also providing various possibilities for prophage-prophage interactions in bacterial cells. In particular, Escherichia coli strains such as Shiga toxin (Stx)-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) strains have acquired more than 10 prophages (up to 21 prophages), many of which encode type III secretion system (T3SS) effector gene clusters. In these strains, some prophages are present at a single locus in tandem, which is usually interpreted as the integration of phages that use the same attachment (att) sequence. Here, we present phages integrating into T3SS effector gene cluster-associated loci in prophages, which are widely distributed in STEC and EPEC. Some of the phages integrated into prophages are Stx-encoding phages (Stx phages) and have induced the duplication of Stx phages in a single cell. The identified attB sequences in prophage genomes are apparently derived from host chromosomes. In addition, two or three different attB sequences are present in some prophages, which results in the generation of prophage clusters in various complex configurations. These phages integrating into prophages represent a medically and biologically important type of inter-phage interaction that promotes the accumulation of T3SS effector genes in STEC and EPEC, the duplication of Stx phages in STEC, and the conversion of EPEC to STEC and that may be distributed in other types of E. coli strains as well as other prophage-rich bacterial species.
Highlights
Horizontal gene transfer (HGT) is an important mechanism for generating genetic and phenotypic variations in bacteria [1,2,3]
Multiple phages are often integrated in a host chromosome as prophages, carrying various novel virulence-related genetic determinants into host bacteria and providing various possibilities for prophage-prophage interactions in bacterial cells. Escherichia coli strains such as Shiga toxin (Stx)-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) strains have acquired more than 10 prophages, many of which encode type III secretion system (T3SS) effector gene clusters
Multiple prophages are often integrated in a bacterial host chromosome and some are present at a single locus in tandem
Summary
Horizontal gene transfer (HGT) is an important mechanism for generating genetic and phenotypic variations in bacteria [1,2,3]. Phages are major players in HGT, and many temperate phages that confer virulence potential to host bacteria through the transfer of virulence-related genes have been identified [4]. Most temperate phages integrate their genomes into host chromosomes by site-specific recombination to become a part of the chromosomes as prophages and enter a lysogenic cycle. Recombination takes place between the homologous sequences of phage and host DNA (attP and attB, respectively) and is mediated by a phage-encoded integrase [5]. Many bacterial species/strains contain multiple prophages [6,7,8], providing various possibilities for prophage-prophage interactions [9,10]. Escherichia coli strains such as Shiga toxin (Stx)-producing E. coli (STEC) strains have acquired more than 10 prophages (up to 21) [11,12,13,14], and some of the prophages are located at the same loci in tandem
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
