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1 TEDA School of Biological Sciences and Biotechnology, Nankai University, 23 HongDa Street, TEDA, Tianjin 300457, P. R. China
2 Tianjin Key Laboratory for Microbial Functional Genomics, Nankai University, 23 HongDa Street, TEDA, Tianjin 300457, P. R. China
3 N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation
4 College of Life Sciences, Nankai University, Tianjin 300071, P. R. China
5 School of Molecular and Microbial Biosciences (G08), University of Sydney, Sydney, NSW 2006, Australia
Correspondence
Lei Wang
wanglei{at}nankai.edu.cn
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
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3)-
-L-Rhap-(13)--L-Rhap-(12)--D-Glcp-(13)--D-GlcpNAc-(1. This differs from the structure reported earlier for S. dysenteriae type 1 by having a glucose (Glc) residue in place of a galactose (Gal) residue. The two bacteria also have the same genes for O antigen synthesis, with the same organization and high level of DNA identity, except that in S. dysenteriae type 1 wbbG is interrupted by a deletion, and a galactosyltransferase gene wbbP located on a plasmid is responsible for the transfer of galactose to make a novel antigenic epitope of the O antigen. The S. dysenteriae type 1 O antigen was reconstructed by replacing the E. coli O148 wbbG gene with the wbbP gene, and it had the LPS structure and antigenic properties of S. dysenteriae type 1, indicating that the S. dysenteriae type 1 O antigen evolved from that of E. coli O148. It was also confirmed that wbbG of E. coli O148 is a glucosyltransferase gene, and two serotype-specific genes of E. coli O148 and S. dysenteriae type 1 were identified.
The GenBank/EMBL/DDBJ accession number for the sequence reported in this paper is DQ167407.
These authors contributed equally to this work.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
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and chemical structural data (Parolis et al., 1997), which also indicates the close relationship between Shigella and E. coli. It has been proposed that Shigella originated from E. coli in the Neolithic about 10 000 years ago when agriculture had been developed (Ochman et al., 1983; Pupo et al., 2000). The O antigen forms unique to Shigella were proposed to have been obtained since the Shigella mode of pathogenicity arose in E. coli (Wang et al., 2001b). The O antigen, as part of the LPS in the outer membrane of Gram-negative bacteria, is a major target of both the immune system and bacteriophages, and plays an important role in the bacterium–host interplay. It is one of the most variable cell constituents and also plays an important role in virulence. Genes for O antigen synthesis are normally clustered between galF and gnd in the chromosome of E. coli.
Of Shigella serotypes, S. dysenteriae type 1 was the first described, and it attracts special attention for frequency of epidemics, the severity of symptoms, high attack rate, high case-fatality rate, and various complications (Bennish et al., 1990). It was responsible for large dysentery epidemics in Guatemala and other parts of Central America (Mendizabal-Morris et al., 1971), Bangladesh (Ronsmans et al., 1988), Zaire (Group, 1995), Kenya (Iijima et al., 1995), and recently West Africa (Guerin et al., 2003) and India (Pazhani et al., 2004). The O antigen of S. dysenteriae type 1 is essential for virulence, and there is indirect evidence that antibodies against the O antigen are protective (Passwell et al., 2001; Robbins et al., 1992; Taylor et al., 1993). The O antigen consists of tetrasaccharide repeating units of the following structure: 3)--L-rhap-(13)--L-rhap-(12)--D-Galp-(13)--D-GlcpNAc-(1 (Dmitriev et al., 1976). The enzymes for the biosynthesis of O antigen are encoded by an O antigen gene cluster and the wbbP gene (previously known as rfpB), located on the chromosome near the his locus and a 9 kb plasmid pHW400, respectively (Gohmann et al., 1994). The wbbP gene was shown to encode a membrane-bound galactosyltransferase, adding the second sugar of the structure shown above. A number of E. coli and Shigellla O antigen gene clusters have been cloned and characterized (Reeves & Wang, 2002), with Shigella sonnei the only other example with genes essential for O antigen synthesis being on a plasmid (Shepherd et al., 2000). The presence of this essential gene on a plasmid indicated that the galactose component of the S. dysenteriae type 1 O antigen was gained recently.
E. coli O148 : H28 is one of the most common causes of diarrhoea in children in developing countries as well as in travellers to these areas (Black, 1986). In this study, the E. coli O148 O antigen repeating unit was shown to differ from that of S. dysenteriae type 1 only by the presence of a glucose residue in place of the galactose residue. The genes and organization of the O antigen gene cluster were shown to be the same in both bacteria, except that wbbG is interrupted by a deletion in S. dysenteriae type 1, which together with the presence in S. dysenteriae type 1 of wbbP accounts for the difference in structure. After deleting wbbG in E. coli O148 and cloning the S. dysenteriae type 1 wbbP gene into the O antigen deficient mutant strain, the construct strain was shown to have the same O antigen structure as S. dysenteriae type 1. Therefore, wbbG was shown to be responsible for transferring glucose to N-acetylglucosamine (GlcNAc) in E. coli O148 and it also appears that S. dysenteriae type 1 gained its current O antigen gene cluster from E. coli O148. Genes specific to E. coli O148 and S. dysenteriae type 1 were identified by screening strains representing 186 E. coli serotypes including Shigella.
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METHODS |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
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) and S. dysenteriae type 1 type strain LSPQ3472 (Pupo et al., 2000) were from the Institute of Medical and Veterinary Science, Adelaide, Australia. All other Shigella and E. coli strains used were previously described (Feng et al., 2004). E. coli DH5 was used as a host strain for plasmids throughout the study. When required, antibiotics were included at the following concentration: ampicillin 100 µg ml–1 and chloramphenicol 10 µg ml–1.
Construction of a random DNase I shotgun bank.
Chromosomal DNA was prepared as previously described (Bastin & Reeves, 1995). Primers wl-1098 (5'-ATTGGTAGCTGTAAGCCAAGGGCGGTAGCGT-3') and wl-1524 (5'-TAGTCGCGCTGNGCCTGGATTAAGTTCGC-3'), based on the JUMPStart and gnd gene, respectively, were used to amplify the E. coli O148 O antigen gene cluster by using the Expand Long Template PCR system (Roche). PCR amplifications were in a final volume of 50 µl containing 1 µl purified DNA, 10 mM dNTP mix and 50 pmol each primer. The PCR conditions were as follows: 1 cycle 94 °C for 2 min, 30 cycles 94 °C for 15 s, 60 °C for 30 s, 68 °C for 15 min, final extension 68 °C for 5 min. To limit any PCR errors, five individual PCR products were pooled. The PCR products were digested with DNase I, and the resulting DNA fragments were cloned into pGEM-T Easy to produce a bank by using the method described previously (Wang & Reeves, 1998).
Sequencing and analysis.
The plasmid DNA template used for sequencing was prepared by the method of Sambrook et al. (1989). Sequencing was carried out with an ABI PRISM 3730 automated DNA sequencer using ABI BigDye terminator chemistry. The Staden package (Staden, 1996) and the Artemis program (Rutherford et al., 2000) were used for sequence assembly and gene annotation, respectively. The BLOCKMAKER program (Henikoff et al., 1995) was used for searching conserved motifs. BLAST and PSI-BLAST (Altschul et al., 1997) were used for searching databases, including GenBank and the Pfam protein motif database (Bateman et al., 2002), for possible gene functions. The algorithm of Eisenberg et al. (1984) was used to identify potential transmembrane segments. Sequence alignment and comparison were done with the CLUSTALW program (Thompson et al., 1994).
Construction of an E. coli O148 wbbG knockout mutant.
The wbbG gene was replaced by a chloramphenicol acetyltransferase (CAT) gene by using the Red recombination system of phage lambda (Datsenko & Wanner, 2000; Yu et al., 2000). The CAT gene was PCR amplified from plasmid pKK232-8 (Pharmacia) by using primers binding to the 5' and 3' ends of the gene, and each primer carried 40 bp based on the E. coli O148 DNA which flanks wbbG: wl-1333 (5'-ATAATACATATCCAAGTGTTGCCGAAAATGTCTGGGGTTCTTCAGGAGCTAAGGAAGCTA-3') and wl-1334 (5'-TTCAACCATGATATCTTTGGTGAAATGCTTTAAGACATATAATTACGCCCCGCCCTGCCA-3'). The wbbG : : cat PCR product was gel-purified using the UNIQ-10 Gel Extraction Kit (Sangon, Shanghai, China) and transformed into an E. coli O148 strain carrying pKD20. Chloramphenicol-resistant transformants were selected after induction of the Red genes by the protocol described by Datsenko & Wanner (2000). Gene replacement was verified by PCR and sequencing using the primer pairs wl-1337 (5'-CGTATGCGTTCGTATGGC-3')/wl-1335 (5'-TCTTTACGATGCGATTGG-3') and wl-1336 (5'-GGATAGTGTTCACCCTTGTT-3')/wl-1338 (5'-AGACGGTATAACCACGAC-3'), which are located in cat and wbbG flanking genes. One positive colony was retained as E. coli O148 strain H1229.
Cloning of the S. dysenteriae type 1 wbbP gene into E. coli O148 derivative H1229.
The wbbP gene and its own promoter were PCR-amplified from the S. dysenteriae type 1 plasmid using primer pair wl-4109 (5'-ACTGGAATTCACATAATTTTTACTTATCAA-3') and wl-2152 (5'-AGTGGGATCCGAATGAATCAGAGCCGC-3') bearing EcoRI and BamHI restriction sites (not present elsewhere in the amplification product). The PCR product was digested with EcoRI and BamHI and ligated into the vector pUC19 digested using the same two enzymes. The plasmid pLW1059 was transformed into E. coli O148 strain H1229 and a positive colony was retained as E. coli O148 strain H1230.
Electroporation.
All electroporations were carried out in a Bio-Rad GenePulser apparatus using 0.2 cm gap cuvettes. Preparation of E. coli electrocompetent cells and electroporation were performed using standard protocols (Ausubel et al., 1999). The E. coli cultures electroporated with the wbbG : : cat PCR product were incubated at 37 °C for 3 h before plating on selective plates.
Serological tests.
The production of S. dysenteriae type 1 O antigen was determined by slide agglutination with S. dysenteriae type 1 type-specific antiserum. A fresh overnight bacterial culture in liquid Luria–Bertani medium was used as the antigen for slide agglutination tests.
Bacterial cultivation and extraction of the O antigen.
LPS of E. coli O148 and E. coli O148 strain H1230 (1047 and 737 mg, respectively) was extracted from dried cells (12.6 and 8.9 g, respectively) by the phenol/water method (Wang et al., 2001a) and purified by precipitation of nucleic acids and proteins with aqueous 50 % trichloroacetic acid as described (Wang et al., 1998). Delipidation of LPS of E. coli O148 and mutant strain H1230 (170 and 160 mg, respectively) was performed with aqueous 2 % acetic acid (6 ml) at 100 °C until lipid A precipitation. The precipitate was removed by centrifugation (13 000 g, 20 min), and the supernatant was fractionated on a column (56x2.6 cm) of Sephadex G-50 (S) (Amersham Biosciences) in 0.05 M pyridinium acetate buffer pH 4.5 monitored using a differential refractometer (Knauer). High-molecular-mass polysaccharides were obtained in yields of 40 % and 35 %, respectively, of the LPS weight.
Chemical analyses of the O antigen.
The polysaccharides were hydrolysed with 2 M CF3CO2H (120 °C, 2 h) and sugars were identified by GLC of the alditol acetates on a Hewlett Packard 5890 chromatograph equipped with an Ultra-2 column (Supelco) using a temperature gradient of 160 °C to 290 °C at 3 °C min–1. The absolute configurations of the monosaccharides were determined by GLC of the acetylated (–)-2-octyl glycosides as described by Leontein & Lonngren (1993).
NMR spectroscopy analyses of the O antigen.
Samples were deuterium-exchanged by freeze-drying twice from D2O and then examined as solutions in 99.96 % D2O at 27 °C. NMR spectra were recorded on a Bruker DRX-500 spectrometer using internal acetone (
H 2.225, C 31.45) as reference. Two-dimensional NMR spectra were obtained using standard Bruker software, and the Bruker XWINNMR 2.6 program was used to acquire and process the NMR data. Mixing times of 200 and 100 ms were used in total correlation spectroscopy (TOCSY) and rotating Overhauser effect spectroscopy (ROESY) experiments, respectively.
PCR specificity assay.
Chromosomal DNA was prepared from 186 E. coli strains, including Shigella strains of different O antigen serotypes. The quality of DNA was examined by PCR amplification of the mdh gene (encoding malate dehydrogenase and present as a housekeeping gene in E. coli) by using primers as described previously (Pupo et al., 1997). A total of 14 pools of DNA were made, each containing DNA from 15–20 E. coli or Shigella O serotypes as described previously (Feng et al., 2004). The pools were screened by PCR by using primers based on E. coli O148 and S. dysenteriae type 1 specific genes wzx [wl-2412 (5'-TTCCCGTTTATAGTTCTTC-3')/wl-2413 (5'-TTTGCCACAACATAGTCA-3'); wl-2414 (5'-CAACAACAATCGCTAAAC-3')/wl-2415 (5'-TGAAATAATGGCAGGTAG-3')] and wzy [wl-2416 (5'-GTCTTAATAGCCAATGCG-3')/wl-2417 (5'-GATAAAGCGAACAGTCCA-3'); wl-2418 (5'-GGAGTGGAAGGGTTGTTT-3')/wl-2419 (5'-GGGAGCGTGACATTCTTT-3')]. Each PCR was carried out in a 25 µl (total volume) mixture, and 15 µl of the mixture was loaded on an agarose gel to check for amplified DNA.
Other methods.
Membrane preparation, SDS-PAGE, and silver staining for visualizing the LPS were carried out as described by Wang & Reeves (1994).
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RESULTS AND DISCUSSION |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
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). Sugar analysis after full acid hydrolysis of the polysaccharide revealed rhamnose (Rha), glucose and glucosamine (GlcN) in the ratios 1.2 : 1 : 0.2. GLC of the acetylated glycosides with (S)-2-octanol showed that glucosamine and glucose have the D configuration while rhamnose has the L configuration.
The 13C NMR spectrum of the polysaccharide (Fig. 1, top) contained signals for four anomeric carbons at 95.6–103.4, one nitrogen-bearing carbon (C-2 of GlcN) at 53.4, two non-substituted HOCH2-C groups at 61.7 (double signal), two CH3-C groups (C-6 of Rha) at 18.1 and 18.3, one N-acetyl group at 23.6 (CH3) and 175.5 (CO), and 15 other carbons in the region 68.0–80.0 Accordingly, the 1H NMR spectrum of the polysaccharide contained signals for four anomeric protons at 5.02–5.53, one N-acetyl group at 2.07 and two methyl groups of rhamnose at 1.29 and 1.33, as well as signals of the other sugar protons. Therefore, the polysaccharide is regular and has a repeating unit containing one glucose, one glucosamine and two rhamnose residues.
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). Based on the coupling constant values estimated from the two-dimensional spectra, the spin systems were assigned to two rhamnose residues (RhaI and RhaII) and one residue each of GlcNAc and Glc. The spin system for GlcNAc was recognized by a correlation between the nitrogen-bearing carbon (C-2) and H-2 at 53.4/4.12 in the 1H,13C HSQC spectrum.
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3 Hz indicated that Glc and GlcNA are -linked, and the position of the signals for C-5 at 70.8 indicated that RhaI and RhaII are -linked too (compare published data: Jansson et al., 1989). The pyranose form of all monosaccharide residues was demonstrated by the absence from the 13C NMR spectrum of any signals for non-anomeric sugar carbons at a lower field than 80 (Bock & Pedersen, 1983).
Relatively low-field positions of the signals for C-3 of RhaI and RhaII, C-2 of Glc and C-3 of GlcNAc at 76.4, 79.5, 78.0 and 77.1, respectively, as compared with their positions in the corresponding non-substituted monosaccharides (Lipkind et al., 1988), demonstrated the modes of glycosylation of the monosaccharides in the repeating unit.
The sequence of the sugar residues was determined by a 1H,1H ROESY experiment, which revealed strong interresidue RhaI H-1/RhaII H-3; RhaII H-1/Glc H-2; Glc H-1/GlcNAc H-3 and GlcNAc H-1/RhaI H-3 cross-peaks at 5.09/3.86; 5.08/3.64; 5.53/4.04 and 5.02/3.92, respectively. This pattern was confirmed by the 1H,13C HMBC experiment (data not shown), and it was concluded that the O antigen of E. coli O148 has the structure shown in Fig. 2.
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), which was shown to differ from the parent form only by replacement of 2)--D-glcp-(1 by 2)--D-Galp-(1 (Fig. 2). Thus, E. coli O148 derivative H1230 has the same O antigen structure as S. dysenteriae type 1.
The E. coli O148 and S. dysenteriae type 1 O antigen gene clusters are closely related
A sequence of 10 241 bases, including gnd (positions 8902–10241), was obtained from E. coli O148 strain E 519-66. Nine ORFs excluding gnd were identified, all transcribed from JUMPstart to gnd (Fig. 3). Functions of each ORF in the E. coli O148 O antigen gene cluster were predicted on the basis of homology by searching available databases and are summarized in Table 3.
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ORFs 5–8 were identified as wzx, wzy, wbbR and wbbQ respectively, based on the high level of identity (97–99 %) of the genes to those of S. dysenteriae type 1. In S. dysenteriae type 1, wzx, wzy, wbbR and wbbQ are proposed to encode O unit flippase, O antigen polymerase, rhamnosyltransferase II and rhamnosyltransferase I, respectively (Klena & Schnaitman, 1993; Sturm et al., 1986). They are presumed to have the same functions in E. coli O148.
ORF 9 was confirmed to be the glucosyltransferase gene (see below) and named as wbbG.
The O antigen gene clusters of E. coli O148 and S. dysenteriae type 1 have the same genes in the same order with DNA identity ranging from 89.8 % to 99.5 % (Fig. 3). However, wbbG in S. dysenteriae type 1 has a deletion of 22 bases flanked by 8 bp direct repeat sequences (Fig. 4), which generated a frame-shift and stop codon. ORF 9 was not assigned a function in S. dysenteriae type 1 (Klena & Schnaitman, 1993).
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), based essentially on the claim that the presence of the wbbP gene conferred addition of galactose to the E. coli LPS core. However, given the current understanding of the role of wecA in E. coli and Shigella O antigen synthesis, we consider that conclusion most improbable, and have shown GlcNAc as first sugar of the repeat unit in Fig. 2.
Construction of a mimic of the S. dysenteriae type 1 O antigen from E. coli O148 and identification of the glucosyltransferase gene
A wbbG knockout mutant of E. coli O148 was constructed by replacing it with a CAT gene. This mutant, named H1229, produced no O antigen, whereas the wild-type strain E 519-66 produced normal LPS (Fig. 5). The wbbP gene and its own promoter were cloned from S. dysenteriae type 1 into pUC19, and the resultant plasmid pLW1059 was electroporated into H1229 to give strain H1230.
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), showing that the plasmid pLW1059 could complement the mutation in strain H1229. Slide agglutination tests showed that strain H1230 reacted with S. dysenteriae type 1 specific antiserum while the E. coli O148 type strain E 519-66 did not. Using the same chemical and NMR spectroscopy (Fig. 1, bottom; Tables 1 and 2) approaches as described above, the O antigen structure of strain H1230 was shown to differ from the parent form only by replacement of the 2)--D-glcp-(1 unit by a 2)--D-Galp-(1 unit and, hence, to be same as that of S. dysenteriae type 1 (Fig. 2). It can be seen in Fig. 5 that the replacement of glucose by galactose in E. coli O148 has not affected the spacing in the LPS ‘ladder’ of molecules with increasing number of repeat units. The high-molecular-mass LPS has a modal distribution similar to that of the parent E. coli O148 strain, with maximum staining at about 19 repeat units, whereas the S. dysenteriae type 1 strain has maximum staining at about 13 repeat units.
These findings confirmed that wbbG is the glucosyltransferase gene responsible for transferring UDP-glucose to GlcNAc via an -1,3-linkage in the O antigen of E. coli O148. The protein encoded by wbbG belongs to the glycosyltransferase group 1 (PF00534, E value=1.7x10–31). It also has 33 and 31 % identity (50 and 52 % similarity) to WbsH of E. coli O128 and WbgM of E. coli O55, both of which are putative glycosyltransferases (Shao et al., 2003; Wang et al., 2002).
The fact that the E. coli O148 RhaII-(1 2)--D-glcp link is replaced by a rhaii-(1 2)--D-Galp in derivative strain H1230 shows that the E. coli O148 RhaII transferase is relaxed for glucose or galactose as acceptor sugar, and thus no change in this transferase gene would have been required for the change in O antigen structure.
S. dysenteriae type 1 gained its O antigen genes from E. coli O148
The above data suggest that the S. dysenteriae type 1 O antigen gene cluster is derived from the E. coli O148 gene cluster by loss of the proposed glucosyltransferase gene wbbG and gain of a plasmid-borne galactosyltranferase. The S. dysenteriae type 1 O antigen is one of those not otherwise known to occur in E. coli but is shown here to be derived from the E. coli O148 O antigen.
Although the exact origin of the galactosyltransferase gene is unknown, it may well have been transferred from another species in the human enteric tract on the plasmid, which presumably arose by transfer of a galactosyltranferase gene from a typical polysaccharide gene cluster to a plasmid. It is most probable that the plasmid was gained before the inactivation of the glucosyltransferase gene wbbG, as with neither wbbG or wbbP, the O unit could not be completed and the LPS would lack O antigen.
MLEE and mdh sequence data show that E. coli O148 : H28 and S. dysenteriae type 1 are not very closely related (Pupo et al., 1997). However, the E. coli O148 O antigen is found in association with several H antigens and further work would be needed to determine if S. dysenteriae type 1 was derived from a different E. coli O148 serotype.
Identification of E. coli O148 and S. dysenteriae type 1 specific genes
PCR assays based on specific genes have been developed for many pathogenic E. coli strains such as E. coli O157 and O111 (Wang et al., 1998; Wang & Reeves, 1998). Two pairs of primers designed for each of wzx and wzy from E. coli O148 were shown to be specific to E. coli O148 and S. dysenteriae type 1 by screening against 186 O serotypes of E. coli and Shigella strains by PCR. It would also be possible to distinguish the two closely related O antigens by use of primers for the plasmid-encoded wbbP gene found only in S. dysenteriae type 1.
Concluding remarks
In summary, the E. coli O148 O antigen structure and gene cluster were elucidated. These data showed that E. coli O148 has a similar O antigen and gene cluster to S. dysenteriae type 1, and a mimic of S. dysenteriae type 1 O antigen was constructed from E. coli O148. Based on these results, it is concluded that S. dysenteriae type 1 gained its O antigen from E. coli O148. In addition, a glucosyltransferase gene of E. coli O148 was identified and two genes were confirmed to be serotype-specific to E. coli O148 and S. dysenteriae type 1.
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ACKNOWLEDGEMENTS |
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Edited by: N. J. High
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
|---|
Ausubel, F. M., Brent, R., Kingston, R. E., Moore, D. D., Seidman, J. G., Smith, J. A. & Struhl, K. E. (1999). Current Protocols in Molecular Biology. New York: Wiley.
Bastin, D. A. & Reeves, P. R. (1995). Sequence and analysis of the O antigen gene (rfb) cluster of Escherichia coli O111. Gene 164, 17–23.[CrossRef][Medline]
Bateman, A., Birney, E., Cerruti, L., Durbin, R., Etwiller, L., Eddy, S. R., Griffiths-Jones, S. Howe K. L., Marshall, M. & Sonnhammer, E. L. (2002). The Pfam protein families database. Nucleic Acids Res 30, 276–280.
Bennish, M. L., Harris, J. R., Wojtyniak, B. J. & Struelens, M. (1990). Death in shigellosis: incidence and risk factors in hospitalized patients. J Infect Dis 160, 500–506.
Black, R. E. (1986). The epidemiology of cholera and enterotoxigenic Escherichia coli diarrheal disease. In Development of Vaccines and Drugs Against Diarrhea, pp. 23–32. Edited by J. Holmgren, A. Lindberg & R. Mollby. Lund, Sweden: Studentlitteratur.
Bock, K. & Pedersen, C. (1983). Carbon-13 nuclear magnetic resonance spectroscopy of monosaccharides. Adv Carbohydr Chem Biochem 41, 27–66.
Datsenko, K. A. & Wanner, B. L. (2000). One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products. Proc Natl Acad Sci U S A 97, 6640–6645.
Dmitriev, B. A., Knirel, Y. A., Kochetkov, N. K. & Hofman, I. L. (1976). Somatic antigens of Shigella. Structural investigation on the O-specific polysaccharide chain of Shigella dysenteriae type 1 lipopolysaccharide. Eur J Biochem 66, 559–566.[Medline]
Eisenberg, D., Schwarz, E., Komaromy, M. & Wall, R. (1984). Analysis of membrane and surface protein sequences with the hydrophobic moment plot. J Mol Biol 179, 125–142.[CrossRef][Medline]
Ewing, W. H. (1986). Edwards and Ewing's Identification of the Enterobacteriaceae, 4th edn. Amsterdam: Elsevier Science Publishers.
Feng, L., Wang, W., Tao, J., Guo, H., Krause, G., Beutin, L. & Wang, L. (2004). Identification of Escherichia coli O114 O-antigen gene cluster and development of an O114 serogroup-specific PCR assay. J Clin Microbiol 42, 3799–3804.
Gohmann, S., Manning, P. A., Alpert, C. A., Walker, M. J. & Timmis, K. N. (1994). Lipopolysaccharide O-antigen biosynthesis in Shigella dysenteriae serotype 1: analysis of the plasmid-carried rfp determinant. Microb Pathog 16, 53–64.[CrossRef][Medline]
Group, G. E. (1995). Public health impact of Rwandan refugee crisis: what happened in Goma, Zaire, in July 1994? Lancet 345, 339–344.[CrossRef][Medline]
Guerin, P. J., Brasher, C., Baron, E., Mic, D., Grimont, F., Rayan, M., Aavitsland, P. & Legros, D. (2003). Shigella dysenteriae serotype 1 in West Africa: intervention strategy for an outbreak in Sierra Leone. Lancet 362, 705–706.[CrossRef][Medline]
Henikoff, S., Henikoff, J. G., Alford, W. J. & Pietrokovski, S. (1995). Automated construction and graphical presentation of protein blocks from unaligned sequences. Gene 163, GC17–26.[CrossRef][Medline]
Iijima, Y., Oundo, J. O., Taga, K., Saidi, S. M. & Honda, T. (1995). Simultaneous outbreak due to Vibrio cholerae and Shigella dysenteriae in Kenya. Lancet 345, 69–70.[CrossRef][Medline]
Jansson, P. E., Kenne, L. & Widmalm, G. (1989). Computer-assisted structural analysis of polysaccharides with an extended version of CASPER using 1H- and 13C-n.m.r. data. Carbohydr Res 188, 169–191.[CrossRef][Medline]
Klena, J. D. & Schnaitman, C. A. (1993). Function of the rfb gene cluster and the rfe gene in the synthesis of O antigen by Shigella dysenteriae 1. Mol Microbiol 9, 393–402.[CrossRef][Medline]
Leontein, K. & Lonngren, J. (1993). Determination of the absolute configuration of sugars by gas-liquid chromatography of their acetylated 2-octyl glycosides. Methods Carbohydr Chem 9, 87–89.
Lipkind, G. M., Shashkov, A. S., Knirel, Y. A., Vinogradov, E. V. & Kochetkov, N. K. (1988). A computer-assisted structural analysis of regular polysaccharides on the basis of 13C-n.m.r. data. Carbohydr Res 175, 59–75.[CrossRef][Medline]
Mendizabal-Morris, C. A., Mata, L. J., Gangarosa, E. J. & Guzman, G. (1971). Epidemic Shiga-bacillus dysentery in Central America. Derivation of the epidemic and its progression in Guatemala, 1968–69. Am J Trop Med Hyg 20, 927–933.[Medline]
Ochman, H., Whittam, T. S., Caugant, D. A. & Selander, R. K. (1983). Enzyme polymorphism and genetic population structure in Escherichia coli and Shigella. J Gen Microbiol 129, 2715–2726.[Medline]
Parolis, H., Parolis, L. A. & Olivieri, G. (1997). Structural studies on the Shigella-like Escherichia coli O121 O-specific polysaccharide. Carbohydr Res 303, 319–325.[CrossRef][Medline]
Passwell, J. H., Harlev, E., Ashkenazi, S., Chu, C., Miron, D., Ramon, R., Farzan N., Shiloach J., Bryla, D. A. & other authors (2001). Safety and immunogenicity of improved Shigella O-specific polysaccharide-protein conjugate vaccines in adults in Israel. Infect Immun 69, 1351–1357.
Pazhani, G. P., Sarkar, B., Ramamurthy, T., Bhattacharya, S. K., Takeda, Y. & Niyogi, S. K. (2004). Clonal multidrug-resistant Shigella dysenteriae type 1 strains associated with epidemic and sporadic dysenteries in Eastern India. Antimicrob Agents Chemother 48, 681–684.
Pupo, G. M., Karaolis, D. K. R., Lan, R. & Reeves, P. R. (1997). Evolutionary relationships among pathogenic and nonpathogenic Escherichia coli strains inferred from multilocus enzyme electrophoresis and mdh sequence studies. Infect Immun 65, 2685–2692.[Abstract]
Pupo, G. M., Lan, R. & Reeves, P. R. (2000). Multiple independent origins of Shigella clones of Escherichia coli and convergent evolution of many of their characteristics. Proc Natl Acad Sci U S A 97, 10567–10572.
Reeves, P. R. & Wang, L. (2002). Genomic organization of LPS-specific loci. Curr Top Microbiol Immunol 264, 109–135.[Medline]
Robbins, J. B., Chu, C. & Schneerson, R. (1992). Hypothesis for vaccine development: protective immunity to enteric diseases caused by nontyphoidal salmonellae and shigellae may be conferred by serum IgG antibodies to the O-specific polysaccharide of their lipopolysaccharides. Clin Infect Dis 15, 346–361.[Medline]
Ronsmans, C., Bennish, M. L. & Wierzba, T. (1988). Diagnosis and management of dysentery by community health workers. Lancet 2, 552–555.[CrossRef][Medline]
Rutherford, K., Parkhill, J., Crook, J., Horsnell, T., Rice, P., Rajandream, M. A. & Barrell, B. (2000). Artemis: sequence visualisation and annotation. Bioinformatics 16, 944–945.
Sambrook, J., Fritsch, E. F. & Maniatis, T. (1989). Molecular Cloning: a Laboratory Manual, 2nd edn. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory.
Shao, J., Li, M., Jia, Q., Lu, Y. & Wang, P. G. (2003). Sequence of Escherichia coli O128 antigen biosynthesis cluster and functional identification of an alpha-1,2-fucosyltransferase. FEBS Lett 553, 99–103.[CrossRef][Medline]
Shepherd, J. G., Wang, L. & Reeves, P. R. (2000). Comparison of O-antigen gene clusters of Escherichia coli (Shigella) sonnei and Plesiomonas shigelloides O17: sonnei gained its current plasmid-borne O-antigen genes from P. shigelloides in a recent event. Infect Immun 68, 6056–6061.
Staden, R. (1996). The Staden sequence analysis package. Mol Biotechnol 5, 233–241.[Medline]
Sturm, S., Jann, B., Jann, K., Fortnagel, P. & Timmis, K. N. (1986). Genetic and biochemical analysis of Shigella dysenteriae 1 O antigen polysaccharide biosynthesis in Escherichia coli K-12: structure and function of the rfb gene cluster. Microb Pathog 1, 307–324.[CrossRef][Medline]
Taylor, D. N., Trofa, A. C., Sadoff, J., Chu, C., Bryla, D., Shiloach, J., Cohen, D., Ashkenazi, S., Lerman, Y. & other authors (1993). Synthesis, characterization, and clinical evaluation of conjugate vaccines composed of the O-specific polysaccharides of Shigella dysenteriae type 1, Shigella flexneri type 2a, and Shigella sonnei (Plesiomonas shigelloides) bound to bacterial toxoids. Infect Immun 61, 3678–3687.
Thompson, J. D., Higgins, D. G. & Gibson, T. J. (1994). CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position specifc gap penalties and weight matrix choice. Nucleic Acids Res 22, 4673–4680.
Wang, L. & Reeves, P. R. (1994). Involvement of the galactosyl-1-phosphate transferase encoded by the Salmonella enterica rfbP gene in O antigen subunit processing. J Bacteriol 176, 4348–4356.
Wang, L. & Reeves, P. R. (1998). Organization of Escherichia coli O157 O antigen gene cluster and identification of its specific genes. Infect Immun 66, 3545–3551.
Wang, L., Curd, H., Qu, W. & Reeves, P. R. (1998). Sequencing of Escherichia coli O111 O antigen gene cluster and identification of O111 specific genes. J Clin Microbiol 36, 3182–3187.
Wang, L., Briggs, C. E., Rothemund, D., Fratamico, P., Luchansky, J. B. & Reeves, P. R. (2001a). Sequence of the E. coli O104 antigen gene cluster and identification of O104 specific genes. Gene 270, 231–236.[CrossRef][Medline]
Wang, L., Qu, W. & Reeves, P. R. (2001b). Sequence analysis of four Shigella boydii O-antigen loci: implication for Escherichia coli and Shigella relationships. Infect Immun 69, 6923–6930.
Wang, L., Huskic, S., Cisterne, A., Rothemund, D. & Reeves, P. R. (2002). The O-antigen gene cluster of Escherichia coli O55 : H7 and identification of a new UDP-GlcNAc C4 epimerase gene. J Bacteriol 184, 2620–2625.
Yu, D., Ellis, H. M., Lee, E. C., Jenkins, N. A., Copeland, N. G. & Court, D. L. (2000). An efficient recombination system for chromosome engineering in Escherichia coli. Proc Natl Acad Sci U S A 91, 5978–5983.
Received 10 August 2006;
revised 11 September 2006;
accepted 14 September 2006.
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