Bacteriophage T12 of Streptococcus pyogenes integrates into the gene encoding a serine tRNA

Abstract

SummaryThe region of temperate bacteriophage T12 responsible for integration into the chromosome of Streptococcus pyogenes has been identified. The integrase gene (int ) and the phage attachment site (attP ) are found immediately upstream of the gene for speA, the latter of which is known to be responsible for the production of erythrogenic toxin A (also known as pyrogenic exotoxin A). The integrase gene has a coding capacity for a protein of 41 457 Da, and the Cterminus of the deduced protein is similar to other conserved C-terminal regions typical of phage integrases. Upstream of int is a second open reading frame, which is capable of encoding an acidic protein of 72 amino acids (8744 Da); the position of this region in relation to int suggests it to be the phage excisionase gene (xis). The arms flanking the integrated prophage (attL and attR ) were identified, allowing determination of the sequences of the phage (attP ) and bacterial (attB ) attachment sites. A fragment containing the integrase gene and attP was cloned into a streptococcal suicide vector; when introduced into S. pyogenes by electrotransformation, this plasmid stably integrated into the bacterial chromosome at attB. The insertion site for the phage into the S. pyogenes chromosome was found to be in the anticodon loop of a putative type II gene for a serine tRNA. attP and attB share a region of identity that is 96 bp in length; this region of identity corresponds to the 3Ј end of the tRNA gene such that the coding sequence remains intact after integration of the prophage. The symmetry of the core region of att may set this region apart from previously described phage attachment sites (Campbell, 1992), and may play a role in the biology of this medically important bacteriophage.

MM1, a Temperate Bacteriophage of the Type 23F Spanish/USA Multiresistant Epidemic Clone of Streptococcus pneumoniae : Structural Analysis of the Site-Specific Integration System

“…There are well-characterized examples of site-specific recombination in gram-negative bacteria, especially that of bacteriophage (30). Although the integration system of phages of gram-positive bacteria is less well documented, data are available for several phages of S. aureus (11,31,59), for bacteriophage T12 of Streptococcus pyogenes (36), for the actinophage RP3 (18), and for several lactic acid bacterial phages (8,14,42,57). We have now identified the attP-containing phage DNA, the bacterial attachment site attB, and the host-phage junctions attL and attR of the MM1 prophage.…”

“…Most of these resistances have been achieved as the result of interspecific gene transfers of DNA fragments between pneumococci and phylogenetically close species that colonize the same ecological niche (i.e., the nasopharynx), leading to acquisition of low-affinity penicillinbinding proteins (26). It has been reported that among the mechanisms of DNA transfer, lysogenic conversion by bacteriophages appears to be advantageous in several bacterial systems (36). The role of phages in the evolution and transfer of bacterial virulence determinants is a topic of increasing research (10,58), and the potential use of bacteriophages for therapy and prophylaxis for antibiotic-resistant bacteria has been suggested (3,37).…”

Characterization of a novel Vibrio pathogenicity island (VPI-2) encoding neuraminidase (nanH) among toxigenic Vibrio cholerae isolates

“…These same tRNA genes also serve as integration sites for different bacteriophages in E. coli K-12 and O157 strain EDL933 (Blattner et al, 1997 ;Perna et al, 2001). Furthermore, the serine tRNA locus in particular serves as the insertion site for the vap region from Dichelobacter nodosus (Cheetham et al, 1995), SPI-5 in Salmonella enterica serovar Typhimurium (Wood et al, 1998), an 84 kb pathogenicity island in E. coli O157 strain EDL933 (Perna et al, 2001) and bacteriophage T12 of Streptococcus pyogenes (McShan et al, 1997).…”

Integration and Distribution of Lactobacillus johnsonii Prophages

“…Furthermore, genes that were not linked to any known phage functions were transcribed from the prophages, thus suggesting potential lysogenic conversion genes (e.g., superantigens in S. pyogenes [5] and tRNA in L. johnsonii [Ventura et al, submitted]). Finally, some S. pyogenes prophages also integrated into tRNA genes (15), but this is a characteristic shared with many prophages (8). However, the lack of reconstitution of an intact tRNA gene by Lj965 sequences is unusual.…”