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Bacterial Polysaccharides Suppress Induced Innate Immunity by Calcium Chelation
- Source :
-
Current Biology . Jul2008, Vol. 18 Issue 14, p1078-1083. 6p. - Publication Year :
- 2008
-
Abstract
- Summary: Bacterial pathogens and symbionts must suppress or negate host innate immunity. However, pathogens release conserved oligomeric and polymeric molecules or MAMPs (Microbial Associated Molecular Patterns), which elicit host defenses . Extracellular polysaccharides (EPSs) are key virulence factors in plant and animal pathogenesis, but their precise function in establishing basic compatibility remains unclear . Here, we show that EPSs suppress MAMP-induced signaling in plants through their polyanionic nature and consequent ability to chelate divalent calcium ions . In plants, Ca2+ ion influx to the cytosol from the apoplast (where bacteria multiply ) is a prerequisite for activation of myriad defenses by MAMPs . We show that EPSs from diverse plant and animal pathogens and symbionts bind calcium. EPS-defective mutants or pure MAMPs, such as the flagellin peptide flg22, elicit calcium influx, expression of host defense genes, and downstream resistance. Furthermore, EPSs, produced by wild-type strains or purified, suppress induced responses but do not block flg22-receptor binding in Arabidopsis cells. EPS production was confirmed in planta, and the amounts in bacterial biofilms greatly exceed those required for binding of apoplastic calcium. These data reveal a novel, fundamental role for bacterial EPS in disease establishment, encouraging novel control strategies. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 09609822
- Volume :
- 18
- Issue :
- 14
- Database :
- Academic Search Index
- Journal :
- Current Biology
- Publication Type :
- Academic Journal
- Accession number :
- 33343432
- Full Text :
- https://doi.org/10.1016/j.cub.2008.06.061