Enteropathogenic and enterohaemorrhagic Escherichia coli deliver a novel effector called Cif, which blocks cell cycle G₂/M transition

Abstract

SummaryEnteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli (EHEC) are closely related pathogens. Both use a type III secretion system (TTSS) encoded by the 'locus of enterocyte effacement' (LEE) to subvert and attach to epithelial cells through the injection of a repertoire of effector molecules. Here, we report the identification of a new TTSS translocated effector molecule called Cif, which blocks cell cycle G 2 /M transition and induces the formation of stress fibres through the recruitment of focal adhesions. Cif is not encoded by the LEE but by a lambdoid prophage present in EPEC and EHEC. A cif mutant causes localized effacement of microvilli and intimately attaches to the host cell surface, but is defective in the ability to block mitosis. When expressed in TTSS competent LEE-positive pathogens, Cif is injected into the infected epithelial cells. These cells arrested at the G 2 / M phase displayed accumulation of inactive phosphorylated Cdk1. In conclusion, Cif is a new member of a growing family of bacterial cyclomodulins that subvert the host eukaryotic cell cycle.

Enterohaemorrhagic Escherichia coli: emerging issues on virulence and modes of transmission

“…Two effectors are encoded outside the LEE by lambdoid prophages: Cif [104] and NleA/EspI [62,118]. Blast analysis revealed that homologues of NleA/EspI are encoded by an Stx1-converting phage in EHEC of serotype O84:H4 (unpublished results) or by the phage coding for Cif [104]. Other potential type III effectors encoded outside the LEE have also been identified using a proteomic approach [38].…”

“…Five translocated effectors are encoded by LEE: Tir/EspE [35,88], Map [87], EspF [109], EspG [45] and EspH [169]. Two effectors are encoded outside the LEE by lambdoid prophages: Cif [104] and NleA/EspI [62,118]. Blast analysis revealed that homologues of NleA/EspI are encoded by an Stx1-converting phage in EHEC of serotype O84:H4 (unpublished results) or by the phage coding for Cif [104].…”

Enterohaemorrhagic Escherichia coli serogroup O111 inhibits NF-κB-dependent innate responses in a manner independent of a type III secreted OspG orthologue

“…To remove the kanamycin cassette from E22 escN : : kmlox (Marches et al, 2003), plasmid pJW168 was used (Wild et al, 1998). To delete the escN gene in EHEC strain 13369, a DNA fragment including 500 bp up-and downstream of escN, a kanamycin cassette and flanking FRT (Flp recombination target) sites was prepared by PCR using primers Kmcassette-F and Kmcassette-R (Table 1) and plasmid pKD4 as the template.…”

The ubiquitin system: a critical regulator of innate immunity and pathogen–host interactions

“…These Cif family effectors function as novel glutamine deamidases and prefer to deamidate NEDD8 rather than ubiquitin and thus impair its conjugation to Cullin, which is an essential subunit of the host CRL E3 ligase complexes. 138,139 Other Gram-negative bacterial pathogens Three bacterial DUBs called TssM, YopJ and YopP have recently been identified from B. pseudomallei, Yersinia pseudotuberculosis and Y. enterocolitica, respectively. These DUBs analogously have a part in suppressing host inflammatory signaling pathways.…”