A new cytolethal distending toxin (CDT) from Escherichia coli producing CNF2 blocks HeLa cell division in G2/M phase

Abstract

SummaryEscherichia coli strain 1404, isolated from a septicaemic calf, carries a transferable plasmid called pVir which codes for the cytotoxic necrotizing factor type 2 (CNF2). A 4 h interaction between strain 1404 and HeLa cells induced the formation of giant mononucleated cells blocked in G2/M phase. Mating experiments between strain 1404 and a non-pathogenic recipient strain demonstrated that the factor(s) encoded by pVir mediated the cell-cycle arrest. A 3.3 kb DNA fragment isolated from a DNA bank of pVir was shown to code for the factor(s) causing the cell-cycle arrest. Nucleotide sequence analysis revealed the presence of three genes encoding proteins sharing significant amino acid homology with the cytolethal distending toxins (CDTs) previously isolated from E. coli, Campylobacter jejuni and Shigella dysenteriae. Southern hybridization experiments demonstrated that the pVir of other CNF2-producing E. coli strains contained sequences related to cdt. Although the amino acid sequences amongst CDT diverged significantly, the two other CDTs previously isolated from E. coli were also able to block the HeLa cell cycle. In conclusion, this study demonstrates the mode of action of CDT and will help us to elucidate the role of this emerging toxin family in microbial pathogenesis.

Cytolethal distending toxins in Shiga toxin-producing Escherichia coli: alleles, serotype distribution and biological effects

“…The PCR primers, target sequences and PCR conditions are listed in Table 2. E. coli strains 6468/62 (O86 : H34; cdt-I + ) (Scott & Kaper, 1994), 9142/88 (O128 : H 2 ; cdt-II + ) (Pickett et al, 1994), 1404 (O78; cdt-III + ) (Peres et al, 1997), 28c (O78; cdt-IV + ) (Toth et al, 2003), and 493/89 (O157 : NM; cdt-V + ) (Janka et al, 2003) were used as positive controls. They were kindly provided by H. Karch (University of Münster), who had received the strains from D. A. Scott (University of Maryland School of Medicine), C. L. Pickett (University of Kentucky Medical Center) and E. Oswald (É cole nationale vétérinaire de Toulouse), or were isolated in his laboratory (strain 493/89).…”

“…A total of five different cdt alleles (cdt-I, cdt-II, cdt-III, cdt-IV and cdt-V) have been reported in E. coli (Janka et al, 2003;Peres et al, 1997;Pickett et al, 1994;Scott & Kaper, 1994;Toth et al, 2003), but there is only limited knowledge available on the epidemiology of the strains harbouring these genes and/or producing CDT. The strains have been isolated from patients with diarrhoea (Albert et al, 1996;Ansaruzzaman et al, 2000;Johnson & Lior 1988b;Okeke et al, 2000) and non-intestinal diseases Johnson & Stell, 2000;.…”

An N-terminal Segment of the Active Component of the Bacterial Genotoxin Cytolethal Distending Toxin B (CDTB) Directs CDTB into the Nucleus

“…The cells intoxicated with CDT show a cytopathic effect and distension in cell size, and eventually they die, which has been shown to be a common consequence of CDT treated cells (1)(2)(3)(4). CDT holotoxin is composed of CDTA, -B, and -C, encoded by the cdtA, cdtB, and cdtC genes tandemly located on the cdt locus (1,(5)(6)(7). The CDTinduced G 2 arrest has been ascribed to the inactivation of the Cdc2-cyclin B complex, which is a key molecule for the progression of the cell cycle.…”

“…It has been identified in several pathogenic bacteria including Campylobacter spp., Escherichia coli, Shigella dysenteriae, Haemophilus ducreyi, Helicobacter hepaticus, and Actinobacillus actinomycetemcomitans. The cells intoxicated with CDT show a cytopathic effect and distension in cell size, and eventually they die, which has been shown to be a common consequence of CDT treated cells (1)(2)(3)(4). CDT holotoxin is composed of CDTA, -B, and -C, encoded by the cdtA, cdtB, and cdtC genes tandemly located on the cdt locus (1,(5)(6)(7).…”

Salmonella typhiencodes a functional cytolethal distending toxin that is delivered into host cells by a bacterial-internalization pathway

“…The cellular enlargement involved not only the cytoplasm but also the nucleus, which appeared as twice the normal size. Since then, this toxin has been identified in many other bacterial pathogens, including other strains of E. coli (3), Shigella dysenteriae (4), Haemophilus ducreyi (5), Actinobacillus actinomycetemcomitans (6), and Helicobacter hepaticus (7). The CDT is composed of three subunits, CdtA, CdtB, and CdtC, which form a tripartite complex (8).…”