| shiga-like toxin converting phage of enterohemorrhagic escherichia coli strain 933. | production of shiga-like toxin (slt) by enterohemorrhagic escherichia coli (ehec) is controlled by phage conversion, and specific phages carry either the slt-i or slt-ii operon. ehec strain 933 produces both slt-i and slt-ii. previous studies demonstrated that the vast majority of phages recovered from strain 993 have hexagonal heads with short tails and encode slt-ii. however, conflicting results were obtained concerning the properties of slt-i converting phages from strain 933. the present stu ... | 1989 | 2671581 |
| cloning of genes for production of escherichia coli shiga-like toxin type ii. | genes controlling production of shiga-like toxin type ii (slt-ii) in escherichia coli were cloned from the slt-ii-converting bacteriophage 933w and compared with the shiga-like toxin type i (slt-i) genes previously isolated and described from phage 933j. subcloning analysis identified a region within the 4.9-kilobase ecori fragment of phage 933w that was associated with slt-ii production. experiments with e. coli minicells containing these subclones demonstrated that the 4.9-kilobase ecori fragm ... | 1987 | 2822579 |
| dna probes for shiga-like toxins i and ii and for toxin-converting bacteriophages. | a set of dna probes has been developed to study the genes for shiga-like toxins (slt) and the bacteriophage from which these toxin genes were isolated. under stringent conditions of hybridization (80 to 90% homology), these probes detect strains containing (i) slt i-related genes, (ii) slt ii-related genes, (iii) phage sequences from the slt i-converting phage h19a/933j, and (iv) phage sequences from the slt ii-converting phage 933w. strain characterization by hybridization with the toxin gene p ... | 1988 | 2842369 |
| two toxin-converting phages from escherichia coli o157:h7 strain 933 encode antigenically distinct toxins with similar biologic activities. | escherichia coli o157:h7 strain 933 contains two distinct toxin-converting phages (933j and 933w). the biologic activities and antigenic relationship between the toxins produced by 933j and 933w lysogens of e. coli k-12, as well as the homology of the genes that encode the two toxins, were examined in this study. the 933j and 933w toxins, like shiga toxin produced by shigella dysenteriae type 1, were cytotoxic for the same cell lines, caused paralysis and death in mice, and caused fluid accumula ... | 1986 | 3522426 |
| analysis of the enterohemorrhagic escherichia coli o157 dna region containing lambdoid phage gene p and shiga-like toxin structural genes. | in this study, we determined the nucleotide sequence of the p gene contained within a 5-kb ecori restriction fragment cloned from shiga-like toxin ii (slt-ii)-converting phage 933w of escherichia coli o157:h7 strain edl933. the p gene was 702 bp long and had 95.3% sequence similarity to the p gene of phage lambda. multiple hybridization patterns were obtained when genomic dna fragments were hybridized with both p and slt-i, slt-ii, or slt-iic sequences. all o157 isolates also possessed an analog ... | 1996 | 8975608 |
| functional and genetic analysis of regulatory regions of coliphage h-19b: location of shiga-like toxin and lysis genes suggest a role for phage functions in toxin release. | analysis of the dna sequence of a 17 kb region of the coli lambdoid phage h-19b genome located the genes encoding shiga-like toxin i (stx-i) downstream of the gene encoding the analogue of the phage lambda q transcription activator with its site of action, qut at the associated pr' late promoter, and upstream of the analogues of lambda genes encoding lysis functions. functional studies, including measurement of the effect of h-19b q action on levels of stx expressed from an h-19b prophage, show ... | 1998 | 9680214 |
| sequence of shiga toxin 2 phage 933w from escherichia coli o157:h7: shiga toxin as a phage late-gene product. | lysogenic bacteriophages are major vehicles for the transfer of genetic information between bacteria, including pathogenicity and/or virulence determinants. in the enteric pathogen escherichia coli o157:h7, which causes hemorrhagic colitis and hemolytic-uremic syndrome, shiga toxins 1 and 2 (stx1 and stx2) are phage encoded. the sequence and analysis of the stx2 phage 933w is presented here. we find evidence that the toxin genes are part of a late-phage transcript, suggesting that toxin producti ... | 1999 | 10074068 |
| shiga toxins even when different are encoded at identical positions in the genomes of related temperate bacteriophages. | the nucleotide sequence of an 11,142-bp region including the stx2 operon in the genome of the temperate bacteriophage 933w in the edl933 strain of escherichia coli o157 was determined and compared to the respective regions derived from other lambdoid bacteriophages. in phage 933w, a region of orfs interlinked by overlapping start-stop codons (atga) was detected preceding the toxin gene. these orfs show a high degree of sequence identity to genes of the nin region of phage lambda. immediately dow ... | 1999 | 10628842 |
| escherichia coli o157 strains which caused japanese outbreaks have residues of bacteriophage sequences. | twelve strains of escherichia coli o157 which caused outbreaks in japan were used as dna sources. the sequences of the gene encoding the shiga toxin 2 in all 12 strains were almost identical and the sequences downstream of this gene were similar to that of bacteriophage 933w. | 1999 | 10746172 |
| a comparative study of the immunity region of lambdoid phages including shiga-toxin-converting phages: molecular basis for cross immunity. | comparison of eight lambdoid phages, including three shiga-toxin converting phages, has been carried out with respect to the immunity region, especially the recognition helices of their repressor and cro proteins on the one hand, and operator sequences on the other. some as yet unassigned components of the regulatory circuits have been inferred by computer search. the cross immunity phenomenon shown by phages vt2-sa and lambda is explained on the basis of similarity in their sequences. in additi ... | 2000 | 11245215 |
| isolation of a lysogenic bacteriophage carrying the stx(1(ox3)) gene, which is closely associated with shiga toxin-producing escherichia coli strains from sheep and humans. | a specific pcr for the detection of a variant of the gene encoding shiga toxin 1 (stx(1)) called stx(1(ox3)) (genbank accession no. z36901) was developed. the pcr was used to investigate 148 stx(1)-producing escherichia coli strains from human patients (n = 72), cattle (n = 27), sheep (n = 48), and a goat (n = 1) for the presence of the stx(1(ox3)) gene. the stx(1(ox3)) gene was present in 38 shiga toxin-producing e. coli (stec) strains from sheep belonging to serogroups o5, o125, o128, o146, an ... | 2001 | 11682520 |
| characterization of a shiga toxin-encoding temperate bacteriophage of shigella sonnei. | a shiga toxin (stx)-encoding temperate bacteriophage of shigella sonnei strain cb7888 was investigated for its morphology, dna similarity, host range, and lysogenization in shigella and escherichia coli strains. phage 7888 formed plaques on a broad spectrum of shigella strains belonging to different species and serotypes, including stx-producing shigella dysenteriae type 1. with e. coli, only strains with rough lipopolysaccharide were sensitive to this phage. the phage integrated into the genome ... | 2001 | 11705937 |
| one of two copies of the gene for the activatable shiga toxin type 2d in escherichia coli o91:h21 strain b2f1 is associated with an inducible bacteriophage. | shiga toxin (stx) types 1 and 2 are encoded within intact or defective temperate bacteriophages in stx-producing escherichia coli (stec), and expression of these toxins is linked to bacteriophage induction. among stx2 variants, only stx(2e) from one human stec isolate has been reported to be carried within a toxin-converting phage. in this study, we examined the o91:h21 stec isolate b2f1, which carries two functional alleles for the potent activatable stx2 variant toxin, stx2d, for the presence ... | 2002 | 12117937 |
| shiga toxin 2-converting bacteriophages associated with clonal variability in escherichia coli o157:h7 strains of human origin isolated from a single outbreak. | shiga toxin 2 (stx2)-converting bacteriophages induced from 49 strains of escherichia coli o157:h7 isolated during a recent outbreak of enterocolitis in spain were examined in an attempt to identify the variability due to the stx(2)-converting phages. the bacterial isolates were divided into low-, medium-, and high-phage-production groups on the basis of the number of phages released after mitomycin c induction. low- and medium-phage-production isolates harbored two kinds of phages but released ... | 2003 | 12874335 |
| characterization of a eukaryotic-like tyrosine protein kinase expressed by the shiga toxin-encoding bacteriophage 933w. | the shiga toxin (stx)-encoding bacteriophage 933w contains an open reading frame, stk, with amino acid sequence similarity to the catalytic domain of eukaryotic serine/threonine (ser/thr) protein kinases (pks). eukaryotic pks are related by a common catalytic domain, consisting of invariant and nearly invariant residues necessary for atp binding and phosphotransfer. we demonstrate that rather than a ser/thr kinase, stk encodes a eukaryotic-like tyrosine (tyr) kinase. an affinity-purified recombi ... | 2004 | 15150234 |
| human escherichia coli o157:h7 genetic marker in isolates of bovine origin. | the antiterminator q gene of bacteriophage 933w (q933) was identified upstream of the stx2 gene in 90% of human disease-origin escherichia coli o157:h7 isolates and in 44.5% of bovine isolates. shiga toxin production was higher in q933-positive isolates than q933-negative isolates. this genetic marker may provide a useful molecular tool for epidemiologic studies. | 2004 | 15496255 |
| purification and characterization of the repressor of the shiga toxin-encoding bacteriophage 933w: dna binding, gene regulation, and autocleavage. | the genes encoding shiga toxin (stx), the major virulence factor of shiga toxin-encoding escherichia coli (stec) strains, are carried on lambdoid prophages resident in all known stec strains. the stx genes are expressed only during lytic growth of these temperate bacteriophages. we cloned the gene encoding the repressor of the shiga toxin-encoding bacteriophage 933w and examined the dna binding and transcriptional regulatory activities of the overexpressed, purified protein. typical of nearly al ... | 2004 | 15516580 |
| the operator and early promoter region of the shiga toxin type 2-encoding bacteriophage 933w and control of toxin expression. | the genes encoding shiga toxin (stx), the major virulence factor of shiga toxin-producing escherichia coli, are carried in the genomes of bacteriophages that belong to the lambdoid family of phages. previous studies demonstrated that induction of prophages encoding stx significantly enhances the production and/or release of stx from the bacterium. therefore, factors that regulate the switch between lysogeny and lytic growth, e.g., repressor, operator sites, and associated phage promoters, play i ... | 2004 | 15516581 |
| first-time isolation and characterization of a bacteriophage encoding the shiga toxin 2c variant, which is globally spread in strains of escherichia coli o157. | a bacteriophage encoding the shiga toxin 2c variant (stx2c) was isolated from the human escherichia coli o157 strain cb2851 and shown to form lysogens on the e. coli k-12 laboratory strains c600 and mg1655. production of stx2c was found in the wild-type e. coli o157 strain and the k-12 lysogens and was inducible by growing bacteria in the presence of ciprofloxacin. phage 2851 is the first reported viable bacteriophage which carries an stx(2c) gene. electron micrographs of phage 2851 showed parti ... | 2004 | 15557626 |
| genetic characterization of escherichia coli o157: h7/- strains carrying the stx2 gene but not producing shiga toxin 2. | nine escherichia coli o157: h7/- strains isolated primarily from non-clinical sources in thailand and japan carried the stx(2) gene but did not produce stx2 toxin in a reversed passive latex agglutination (rpla) assay. a strain (edl933) bearing a stx(2) phage (933w) was compared to a strain (thai-12) that was stx2-negative but contained the stx(2) gene. to study the lack of stx2 production, the thai-12 stx(2) gene and its upstream nucleotide sequence were analyzed. the thai-12 stx(2) coding regi ... | 2006 | 16490932 |
| newly identified bacteriophages carrying the stx2g shiga toxin gene isolated from escherichia coli strains in polluted waters. | shiga toxin-converting bacteriophages are the main vehicle involved in horizontal transmission of stx1 and stx2 genes, which has led to the current spread of stx genes among a high number of escherichia coli serotypes and other enterobacteria. several stx gene variants have been described, although some of the variants have never been isolated from inducible bacteriophages. in this study, two stx2g-carrying bacteriophages induced from two different e. coli o2:h25 strains isolated from different ... | 2006 | 16630267 |
| evaluation of the anti-terminator q933 gene as a marker for escherichia coli o157:h7 with high shiga toxin production. | the anti-terminator q933 gene of the bacteriophage 933w was evaluated as a marker for escherichia coli o157:h7 strains with high shiga toxin production. in total, 262 environmental strains of e. coli o157:h7 isolated from feces of beef cattle and the digestive tract of houseflies were screened for the q933 and q21 (anti-terminator q21 of bacteriophage 21) genes by polymerase chain reaction. nine (3.4%) isolates tested positive for q933 alone, 161 (61.5%) were positive for the q21 gene alone, and ... | 2006 | 16972124 |
| modelling the stability of stx lysogens. | shiga-toxin-converting bacteriophages (stx phages) are temperate phages of escherichia coli, and can cause severe human disease. the spread of shiga toxins by stx phages is directly linked to lysogen stability because toxins are only synthesized and released once the lytic cycle is initiated. lysogens of stx phages are known to be less stable than those of the related lambda phage; this is often described in terms of a 'hair-trigger' molecular switch from lysogeny to lysis. we have developed a m ... | 2007 | 17604057 |
| dam methyltransferase is required for stable lysogeny of the shiga toxin (stx2)-encoding bacteriophage 933w of enterohemorrhagic escherichia coli o157:h7. | shiga toxin 2 (stx2), one of the principal virulence factors of enterohemorrhagic escherichia coli, is encoded by 933w, a lambda-like prophage. 933w prophage induction contributes to stx2 production, and here, we provide evidence that dam methyltransferase is essential for maintenance of 933w lysogeny. our findings are consistent with the idea that the 933w prophage has a relatively low threshold for induction, which may promote stx2 production during infection. | 2008 | 17981979 |
| identification and epidemiological description of enterohemorrhagic escherichia coli o157 strains producing low amounts of shiga toxin 2 in aichi prefecture, japan. | out of 68 escherichia coli o157 field isolates tested in vitro for shiga toxin (stx) 2 production, 12 (17.6%) produced no or a limited amount of stx2 (stx 2 non- or low-producing strain; tnlp) even though all 68 possessed the stx(2) gene. the remaining 56 were stx2 high-producing strains. the 12 tnlps carried the q21 gene allele, which encodes a transcription antiterminator q protein and is highly homologous to that of phi21 phage. they also carried nucleotide substitutions and insertions in the ... | 2008 | 19050350 |
| microarray analysis and draft genomes of two escherichia coli o157:h7 lineage ii cattle isolates frik966 and frik2000 investigating lack of shiga toxin expression. | the existence of two separate genetic lineages of escherichia coli o157:h7 has previously been reported, and research indicates that lineage i could be more pathogenic toward human hosts than lineage ii. we have previously shown that lineage i as a group expresses higher levels of shiga toxin 2 (stx2) than lineage ii. to help evaluate why lineage ii strains do not express appreciable levels of this toxin, whole-genome microarrays were performed using agilent custom microarrays. gene expression o ... | 2010 | 20156085 |
| the lysis-lysogeny decision of bacteriophage 933w: a 933w repressor-mediated long distance loop has no role in regulating 933w prm activity. | our data show that unlike bacteriophage λ, repressor bound at o(l) of bacteriophage 933w has no role regulating 933w repressor occupancy of 933w o(r)3 or the transcriptional activity of 933w p(rm). this finding suggests that a cooperative long-range loop between repressor tetramers bound at o(r) and o(l) does not form in bacteriophage 933w. nonetheless, 933w forms lysogens and 933w prophage display a threshold response to uv induction similar to related lambdoid phages. hence, the long range loo ... | 2011 | 21551291 |
| survival of the fittest: a role for phage-encoded eukaryotic-like kinases. | phages are often thought of as mortal enemies of bacteria. this dynamic relationship has led to the evolution of a number of processes in bacteria designed to defeat these attacks. examples of these include blocking phage attachment, crispr, and restriction modification systems. temperate phages provide another source of protection by excluding infection of heterologous phage, thwarting phage production and further infection. this strategy protects the rest of the bacterial population from attac ... | 2011 | 21992081 |