Essential role of the type III secretion system effector NleB in colonization of mice by Citrobacter rodentium.
Attaching and effacing (A/E) pathogens are a significant cause of gastrointestinal illness in humans and animals. All A/E pathogens carry a large pathogenicity island, termed the locus for enterocyte effacement (LEE), which encodes a type III secretion system that translocates several effector proteins into host cells. To identify novel virulence determinants in A/E pathogens, we performed a signature-tagged mutagenesis screen in C57BL/6 mice by using the mouse A/E pathogen Citrobacter rodentium. Five hundred seventy-six derivatives of C. rodentium were tested in pools of 12 mutants. One attenuated mutant carried a transposon insertion in nleB, which encodes a putative effector of the LEE-encoded type III secretion system (T3SS). nleB is present in a genomic pathogenicity island that also encodes another putative effector, NleE, immediately downstream. Using translational fusions with beta-lactamase (TEM-1), we showed that both NleB and NleE were translocated into host cells by the LEE-encoded T3SS of enteropathogenic Escherichia coli. In addition, deletion of the gene encoding NleB in C. rodentium resulted in reduced colonization of mice in single infections and reduced colonic hyperplasia. In contrast, the deletion of other non-LEE-encoded effector genes in C. rodentium, nleC, nleD, or nleE, had no effect on host colonization or disease. These results suggest that nleB encodes an important virulence determinant of A/E pathogens.
Kelly
Michelle
M
Department of Microbiology, Monash University, Victoria 3800, Australia.
Hart
Emily
E
Mundy
Rosanna
R
Marchès
Olivier
O
Wiles
Siouxsie
S
Badea
Luminita
L
Luck
Shelley
S
Tauschek
Marija
M
Frankel
Gad
G
Robins-Browne
Roy M
RM
Hartland
Elizabeth L
EL
D000818:Animals; D001426:Bacterial Proteins / Q000502:physiology*; D001483:Base Sequence; D044082:Citrobacter rodentium / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D003106:Colon / Q000382:microbiology; D017931:DNA Primers; D004756:Enterobacteriaceae Infections / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D044404:Genomic Islands / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016296:Mutagenesis; D021381:Protein Transport / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics / Q000502:physiology*
D001426:Bacterial Proteins; D017931:DNA Primers; D037521:Virulence Factors