Genetic Structure and Distribution of Four Pathogenicity Islands (PAI I536 to PAI IV536) of Uropathogenic Escherichia coli Strain 536

Institut für Molekulare Infektionsbiologie, Universität Würzburg, D-97070 Würzburg, Germany.
Infection and Immunity (Impact Factor: 3.73). 12/2002; 70(11):6365-72. DOI: 10.1128/IAI.70.11.6365-6372.2002
Source: PubMed

ABSTRACT For the uropathogenic Escherichia coli strain 536 (O6:K15:H31), the DNA sequences of three pathogenicity islands (PAIs) (PAI I(536) to PAI III(536)) and their flanking regions (about 270 kb) were determined to further characterize the virulence potential of this strain. PAI I(536) to PAI III(536) exhibit features typical of PAIs, such as (i) association with tRNA-encoding genes; (ii) G+C content differing from that of the host genome; (iii) flanking repeat structures; (iv) a mosaic-like structure comprising a multitude of functional, truncated, and nonfunctional putative open reading frames (ORFs) with known or unknown functions; and (v) the presence of many fragments of mobile genetic elements. PAI I(536) to PAI III(536) range between 68 and 102 kb in size. Although these islands contain several ORFs and known virulence determinants described for PAIs of other extraintestinal pathogenic E. coli (ExPEC) isolates, they also consist of as-yet-unidentified ORFs encoding putative virulence factors. The genetic structure of PAI IV(536), which represents the core element of the so-called high-pathogenicity island encoding a siderophore system initially identified in pathogenic yersiniae, was further characterized by sample sequencing. For the first time, multiple PAI sequences (PAI I(536) to PAI IV(536)) in uropathogenic E. coli were studied and their presence in several wild-type E. coli isolates was extensively investigated. The results obtained suggest that these PAIs or at least large fragments thereof are detectable in other pathogenic E. coli isolates. These results support our view that the acquisition of large DNA regions, such as PAIs, by horizontal gene transfer is an important factor for the evolution of bacterial pathogens.

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Available from: Ulrich Dobrindt, Apr 10, 2014
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    • "Comparative genomic analyses were carried out by Hochhut and colleagues between 536 and another reference strain, CFT073, which revealed at least five pathogenicity islands (PAI I-V536) specific to strain 536 [28],[47],[48]. Strain 536 (O6:K15:H31) is well-characterized and it has been demonstrated that it produces various types of fimbrial adhesins, such as S fimbriae (sfa) and type 1 and P-related fimbriae [49]. The P-related fimbriae genes and S fimbrial adhesins are located on PAI I536 and PAI II536, respectively and deletion mutants in these regions show decreased potency in vivo [49],[50]. "
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    ABSTRACT: Galleria mellonella larvae are an alternative in vivo model for investigating bacterial pathogenicity. Here, we examined the pathogenicity of 71 isolates from five leading uropathogenic E. coli (UPEC) lineages using G. mellonella larvae. Larvae were challenged with a range of inoculum doses to determine the 50% lethal dose (LD50) and for analysis of survival outcome using Kaplan-Meier plots. Virulence was correlated with carriage of a panel of 29 virulence factors (VF). Larvae inoculated with ST69 and ST127 isolates (104 colony-forming units/larvae) showed significantly higher mortality rates than those infected with ST73, ST95 and ST131 isolates, killing 50% of the larvae within 24 hours. Interestingly, ST131 isolates were the least virulent. We observed that ST127 isolates are significantly associated with a higher VF-score than isolates of all other STs tested (P≤0.0001), including ST69 (P<0.02), but one ST127 isolate (strain EC18) was avirulent. Comparative genomic analyses with virulent ST127 strains revealed an IS1 mediated deletion in the O-antigen cluster in strain EC18, which is likely to explain the lack of virulence in the larvae infection model. Virulence in the larvae was not correlated with serotype or phylogenetic group. This study illustrates that G. mellonella are an excellent tool for investigation of the virulence of UPEC strains. The findings also support our suggestion that the incidence of ST127 strains should be monitored, as these isolates have not yet been widely reported, but they clearly have a pathogenic potential greater than that of more widely recognised clones, including ST73, ST95 or ST131.
    PLoS ONE 07/2014; 9(7):e101547. DOI:10.1371/journal.pone.0101547 · 3.23 Impact Factor
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    • "Specifically, SCAZ3_04635 (ATP-dependent clp protease) was homologous with clpE, an ATP-dependent protease from Listeria monocytogenes; clp genes have been shown to play a role in competence, development, and stress survival (thermotolerance) in S. pneumoniae[46]. SCAZ3_04705 (DNA-cytosine methyltransferase) was homologous with a putative DNA methylase from Escherichia coli (strain 536), which is located within a pathogenicity island [47] that included MGEs as an integral part of its evolutionary history [48]. Likewise, SCAZ3_04705 is located within a MGE and its specific function may involve plasmid defense. "
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    ABSTRACT: Background Streptococcus canis is an important opportunistic pathogen of dogs and cats that can also infect a wide range of additional mammals including cows where it can cause mastitis. It is also an emerging human pathogen. Results Here we provide characterization of the first genome sequence for this species, strain FSL S3-227 (milk isolate from a cow with an intra-mammary infection). A diverse array of putative virulence factors was encoded by the S. canis FSL S3-227 genome. Approximately 75% of these gene sequences were homologous to known Streptococcal virulence factors involved in invasion, evasion, and colonization. Present in the genome are multiple potentially mobile genetic elements (MGEs) [plasmid, phage, integrative conjugative element (ICE)] and comparison to other species provided convincing evidence for lateral gene transfer (LGT) between S. canis and two additional bovine mastitis causing pathogens (Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. dysgalactiae), with this transfer possibly contributing to host adaptation. Population structure among isolates obtained from Europe and USA [bovine = 56, canine = 26, and feline = 1] was explored. Ribotyping of all isolates and multi locus sequence typing (MLST) of a subset of the isolates (n = 45) detected significant differentiation between bovine and canine isolates (Fisher exact test: P = 0.0000 [ribotypes], P = 0.0030 [sequence types]), suggesting possible host adaptation of some genotypes. Concurrently, the ancestral clonal complex (54% of isolates) occurred in many tissue types, all hosts, and all geographic locations suggesting the possibility of a wide and diverse niche. Conclusion This study provides evidence highlighting the importance of LGT in the evolution of the bacteria S. canis, specifically, its possible role in host adaptation and acquisition of virulence factors. Furthermore, recent LGT detected between S. canis and human bacteria (Streptococcus urinalis) is cause for concern, as it highlights the possibility for continued acquisition of human virulence factors for this emerging zoonotic pathogen.
    BMC Microbiology 12/2012; 12(1):293. DOI:10.1186/1471-2180-12-293 · 2.73 Impact Factor
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    • "This should not disfavor integration events and indeed we find that the frequency of transposases in this region is not significantly different from the rest of the genome (P = 0.77, 2 test). Furthermore, NS regions integrate some well-known pathogenicity islands encoding tyrosine recombinases (Napolitano et al. 2011), for example, PAI-LEE, PAI-I CFT073 , and PAI-III EDL933 (Blum et al. 1994; McDaniel et al. 1995; Dobrindt et al. 2002). Core genes in these regions have sequence compositions similar to the rest of the genome (51% in GC content, P = 0.2, Wilcoxon test) suggesting this is not the cause of a putative integration bias. "
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    ABSTRACT: Rapid turnover of mobile elements drives the plasticity of bacterial genomes. Integrated bacteriophages (prophages) encode host adaptive traits and represent a sizable fraction of bacterial chromosomes. We hypothesized that natural selection shapes prophage integration patterns relative to the host genome organization. We tested this idea by detecting and studying 500 prophages of 69 strains of Escherichia and Salmonella. Phage integrases often target conserved genes but also intergenic positions, suggesting purifying selection for integration sites. Furthermore, most integration hotspots are conserved between the two host genera. Integration sites seem also selected at the large chromosomal scale, as they are non-randomly organized in terms of the origin-terminus axis and the macrodomain structure. The genes of lambdoid prophages are systematically co-oriented with the bacterial replication fork and display the host high frequency of polarized KOPS motifs required for chromosome segregation. matS motifs are strongly avoided by prophages suggesting counter-selection of motifs disrupting macrodomains. These results show how natural selection for seamless integration of prophages in the chromosome shapes the evolution of the bacterium and the phage. First, integration sites are highly conserved for many millions of years favoring lysogeny over the lytic cycle for temperate phages. Second, the global distribution of prophages is intimately associated with the chromosome structure and the patterns of gene expression. Third, the phage endures selection for DNA motifs that pertain exclusively to the biology of the prophage in the bacterial chromosome. Understanding prophage genetic adaptation sheds new lights on the co-existence of horizontal transfer and organized bacterial genomes.
    Molecular Biology and Evolution 12/2012; 30(4). DOI:10.1093/molbev/mss279 · 9.11 Impact Factor
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