Congo red binding phenotype is associated with hemin binding and increased infectivity of Shigella flexneri in the HeLa cell model.
AUTOR(ES)
Daskaleros, P A
RESUMO
Wild-type isolates of Shigella flexneri bind the dye Congo red from solid media, thus producing red (Crb+) colonies. Mutants which fail to bind the dye produce white colonies (Crb-) and are avirulent in a variety of systems. In S. flexneri the ability to bind Congo red correlates with the ability to bind hemin and protoporphyrin IX. Binding of hemin by Crb+ S. flexneri was observed both in solid media and in liquid assays. Results of competition experiments suggest that Congo red and hemin bind to the same site on the bacterial cell and are retained on the cell surface. Binding of hemin by Crb+ S. flexneri is independent of hemin transport since both Crb+ and Crb- cells can utilize hemin as a sole source of iron. Both Crb- and Crb- organisms were able to grow in HeLa cell lysates, indicating that the gene(s) that is responsible for Congo red binding does not play a role in the acquisition of intracellular heme iron. By using the HeLa cell invasion system, the effect of hemin prebinding on the invasiveness of Crb+ S. flexneri was determined. Crb+ cells which had prebound hemin exhibited increased invasiveness, indicating a possible role for the crb gene product in the initial stages of invasion by S. flexneri.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=260526Documentos Relacionados
- Plasmid-associated adherence of Shigella flexneri in a HeLa cell model.
- Cloning the gene for Congo red binding in Shigella flexneri.
- Shigella flexneri invasion of HeLa cells induces NF-kappa B DNA-binding activity.
- Molecular alteration of the 140-megadalton plasmid associated with loss of virulence and Congo red binding activity in Shigella flexneri.
- A 101-kilodalton heme-binding protein associated with congo red binding and virulence of Shigella flexneri and enteroinvasive Escherichia coli strains.