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Volume 2, Number 4—October 1996

Synopsis

Molecular Mechanisms of Bacterial Virulence: Type III Secretion and Pathogenicity Islands

Joan Mecsas and Evelyn J. Strauss
Author affiliations: Stanford University School of Medicine, Stanford, California

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Table 2

Characteristics of several pathogenicity islands

Organism Name Location Borders Stable ? Foreign origin G+C: % island/ % chromosome Functions Size Ref.
Uropathogenic E. coli 536 Pathogenicity island I, Pai I selCa, 82' • 16 bp direct repeats, derived from selC
• shared motif with Pai II repeats no direct repeats
absent from normal fecal and laboratory strains of E. coli 
-hemolysin I 70 kb 3, 82, 84
Pai II leuXa, 97' • 18 bp direct repeats, derived from leuX
• shared motif with Pai I repeats no direct repeats
absent from normal fecal and laboratory strains of E. coli 
-hemolysin II
prf (fimbriae: adherence to host cells)
transcriptional activators of chromosomal genes 190 kb 3,4, 67, 82, 84
Uropathogenic E. coli J96 Pai I near pheVa, 64' absent from normal fecal and laboratory strains of E. coli 
-hemolysin I
pap (fimbriae: adherence to host cells)
IS element sequences
R plasmid sequences
P4 phage sequences >170 kb 96
Pai II pheRa, 94' 135 bp imperfect direct repeats no direct repeats
absent from normal fecal and laboratory strains of E. coli 
-hemolysin II
prs (fimbriae: adherence to host cells)
cytotoxic necrotizing factor type 1
IS element sequences
P4 phage sequences
OmpR homolog 106 kb 4, 96, 97
Entero-pathogenic E. coli (EPEC) Locus of enterocyte effacement, LEE selCa, 82' no repeats or IS elements found yesb G+C: 39%/51%
not present in closely related, non-AE-producing bacteria mediates formation of AE lesions
type III secretion system 35 kb 63, 83
Salmonella typhimurium Salmonella pathogenicity island 1, SPI 1 between fhl and mutS, 63' no repeats or IS elements found in S. typhimurium; IS3 on one border in certain Salmonella serotypes yesb,c G+C: 42%/52%
absent from E. coli invasion into cultured epithelial cells
type III secretion system 40 kb 28, 68
SPI 2 between ydhE and pykF, 31' yesb G+C: 45%/52%
absent from E. coli; conserved among Salmonella type III secretion system 40 kb 43
Salmonella induced filament gene A, sifA potB/ potC 14 bp direct repeats yes G+C: 41%/52%
direct repeats
absent in E. coli; conserved among Salmonella required for formation of structures associated with Salmonella-associated vacuoles within epithelial cells 1.6 kb 69d
Yersinia pestis Ability to adsorb exogenous pigments, Pgm phoE 2.2 kb direct repeats (=IS100) no G+C: hemin storage region 47%/46-50%; yersiniabactin receptor/ iron-regulated protein region 56-60%/46-50%
direct repeats hemin and congo red binding
pesticin sensitivity
iron acquisition
growth at 37 C in defined medium 102 kb 70, 71
Helicobacter pylori Cytotoxin-associated gene region, Cag glr • 31 bp direct repeats, derived from glutamate racemase gene
• IS605 on one end see text G+C: 35%/38-45%
IS elements
not present in type II strains induction of IL-8 secretion
homologues to membrane-associated proteins: environmental sensors, translocases, permeases, pilus and flagella assembly proteins
IS elements 40 kb e
Vibrio cholerae O139 otnA otnB rfb flanked by two different IS elements IS elements
not present in Vibrio cholerae O1 El Tor capsule and O antigen synthesis (by homology) 35 kb 93, 98
Listeria monocytogenes between prs and ldh No IS elements found yesb not present in several nonpathogenic species escape from vacuole
intra-/inter-cellular spread 9.6 kb 99

atRNA gene
bapparently
cunstable in certain serotypes
dadditional information received in personal communication with M. Stein
eCensini S, et al., 1996, submitted for publication

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