[Show abstract][Hide abstract] ABSTRACT: The K15 capsule determinant of uropathogenic Escherichia coli strain 536 (O6:K15:H31) is part of a novel 79.6-kb pathogenicity island (PAI) designated PAI V536 that is absent from the genome of nonpathogenic E. coli K-12 strain MG1655. PAI V536 shows typical characteristics of a composite PAI that is associated with the pheV tRNA gene and contains the pix fimbriae determinant as well as genes coding for a putative phosphoglycerate transport system, an autotransporter protein, and hypothetical open reading frames. A gene cluster coding for a putative general secretion pathway system, together with a kps(K15) determinant, is localized downstream of a truncated pheV gene ('pheV) also present in this chromosomal region. The distribution of genes present on PAI V536 was studied by PCR in different pathogenic and nonpathogenic E. coli isolates of various sources. Analysis of the 20-kb kps locus revealed a so far unknown genetic organization. Generally, the kps(K15) gene cluster resembles that of group 2 and 3 capsules, where two conserved regions (regions 1 and 3) are located up- or downstream of a highly variable serotype-specific region (region 2). Interestingly, recombination of a group 2 and 3 determinant may have been involved in the evolution of the K15 capsule-encoding gene cluster. Expression of the K15 capsule is important for virulence in a murine model of ascending urinary tract infection but not for serum resistance of E. coli strain 536.
Infection and Immunity 11/2004; 72(10):5993-6001. DOI:10.1128/IAI.72.10.5993-6001.2004 · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Suppression subtractive hybridisation (SSH) was performed to identify genomic differences between the uropathogenic Escherichia coli strain 536 and the non-pathogenic E. coli K-12 strain MG1655. In total, 22 DNA fragments were isolated which were specific for strain 536. Five of these fragments showed homology to known virulence determinants and four fragments matched genes for lipopolysaccharide (LPS) or capsule biosynthesis and a siderophore receptor. Seven fragments did not show any homology to known genes. These fragments may represent parts of putative pathogenicity islands (PAIs). Whereas two fragments were highly specific for uropathogenic E. coli (UPEC), the other fragments could also be detected among the other tested wild-type strains.
[Show abstract][Hide abstract] ABSTRACT: Toxin-specific genes are often located on mobile genetic elements such as phages, plasmids and pathogenicity islands (PAIs). The uropathogenic E. coli strain 536 carries two alpha-hemolysin gene clusters, which are part of the pathogenicity islands I536 and II536, respectively. Using different genetic techniques, two additional PAIs were identified in the genome of the E. coli strain 536, and it is likely that further PAIs are located on the genome of this strain. Pathogenicity islands are often associated with tRNA genes. In the case of the E. coli strain 536, the PAI-associated tRNA gene leuX, which encodes a minor leucyl-tRNA, affects the expression of various virulence traits including alpha-hemolysin production. The exact mode of action of the tRNA5Leu-dependent gene expression has to be identified in the future.
International Journal of Medical Microbiology 11/2000; 290(4-5):307-11. DOI:10.1016/S1438-4221(00)80028-4 · 3.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The species E. coli comprises non pathogenic variants and other strains which are able to cause infectious diseases. In order to identify DNA
fragments which are present in the pathogenic E. coli strain 536 but absent from the non-pathogenic E. coli strain MG1655 we have performed a subtractive hybridization analysis.
We obtained diverse DNA fragments specific for the E. coli strain 536. Sequence data of several cloned subtractive hybridization fragments showed a homology to known virulence genes.
Other E. coli strain 536 specific DNA fragments showed no homology to already known DNA or protein sequences and may represent new virulence
genes on PAIs.
In conclusion subtractive hybridization is a successful method for the identification of strain specific DNA sequences. It
is a useful approach to complement other genomic approaches such as proteome analysis or differential RNA display analysis.
Advances in Experimental Medicine and Biology 02/2000; 485:53-6. DOI:10.1007/0-306-46840-9_6 · 1.96 Impact Factor