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The toxin/immunity network of Burkholderia pseudomallei contact-dependent growth inhibition (CDI) systems.

ABSTRACT: Burkholderia pseudomallei is a category B pathogen and the causative agent of melioidosis--a serious infectious disease that is typically acquired directly from environmental reservoirs. Nearly all B.?pseudomallei strains sequenced to date (> 85 isolates) contain gene clusters that are related to the contact-dependent growth inhibition (CDI) systems of ?-proteobacteria. CDI systems from Escherichia coli and Dickeya dadantii play significant roles in bacterial competition, suggesting these systems may also contribute to the competitive fitness of B.?pseudomallei. Here, we identify 10 distinct CDI systems in B.?pseudomallei based on polymorphisms within the cdiA-CT/cdiI coding regions, which are predicted to encode CdiA-CT/CdiI toxin/immunity protein pairs. Biochemical analysis of three B.?pseudomallei CdiA-CTs revealed that each protein possesses a distinct tRNase activity capable of inhibiting cell growth. These toxin activities are blocked by cognate CdiI immunity proteins, which specifically bind the CdiA-CT and protect cells from growth inhibition. Using Burkholderia thailandensis E264 as a model, we show that a CDI system from B.?pseudomallei 1026b mediates CDI and is capable of delivering CdiA-CT toxins derived from other B.?pseudomallei strains. These results demonstrate that Burkholderia species contain functional CDI systems, which may confer a competitive advantage to these bacteria.

SUBMITTER: Nikolakakis K

PROVIDER: S-EPMC3331888 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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The toxin/immunity network of Burkholderia pseudomallei contact-dependent growth inhibition (CDI) systems.

Nikolakakis Kiel K Amber Saba S Wilbur J Scott JS Diner Elie J EJ Aoki Stephanie K SK Poole Stephen J SJ Tuanyok Apichai A Keim Paul S PS Peacock Sharon S Hayes Christopher S CS Low David A DA

Molecular microbiology 20120404 3

Burkholderia pseudomallei is a category B pathogen and the causative agent of melioidosis--a serious infectious disease that is typically acquired directly from environmental reservoirs. Nearly all B. pseudomallei strains sequenced to date (> 85 isolates) contain gene clusters that are related to the contact-dependent growth inhibition (CDI) systems of γ-proteobacteria. CDI systems from Escherichia coli and Dickeya dadantii play significant roles in bacterial competition, suggesting these system ...[more]

PMID: 22435733

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Project description:Burkholderia species, including opportunistic pathogens in the Burkholderia cepacia complex (Bcc), have genes to produce contact-dependent growth inhibition (CDI) system proteins. CDI is a phenomenon in which Gram-negative bacteria use the toxic C terminus of a polymorphic surface-exposed exoprotein, BcpA, to inhibit the growth of susceptible bacteria upon direct cell-cell contact. Production of a small immunity protein, BcpI, prevents autoinhibition. Although CDI systems appear widespread in Gram-negative bacteria, their function has been primarily examined in several model species. Here we demonstrate that genes encoding predicted CDI systems in Bcc species exhibit considerable diversity. We also show that Burkholderia multivorans, which causes pulmonary infections in patients with cystic fibrosis, expresses genes that encode two CDI systems, both of which appear distinct from the typical Burkholderia-type CDI system. Each system can mediate intrastrain interbacterial competition and contributes to bacterial adherence. Surprisingly, the immunity-protein-encoding bcpI gene of CDI system 1 could be mutated without obvious deleterious effects. We also show that nonpathogenic Burkholderia thailandensis uses CDI to control B. multivorans growth during coculture, providing one of the first examples of interspecies CDI and suggesting that CDI systems could be manipulated to develop therapeutic strategies targeting Bcc pathogens.IMPORTANCE Competition among bacteria affects microbial colonization of environmental niches and host organisms, particularly during polymicrobial infections. The Bcc is a group of environmental bacteria that can cause life-threatening opportunistic infections in patients who have cystic fibrosis or are immunocompromised. Understanding the mechanisms used by these bacterial pathogens to compete with one another may lead to the development of more effective therapies. Findings presented here demonstrate that a Bcc species, Burkholderia multivorans, produces functional CDI system proteins and that growth of this pathogen can be controlled by CDI system proteins produced by neighboring Burkholderia cells.

Dataset Information

The toxin/immunity network of Burkholderia pseudomallei contact-dependent growth inhibition (CDI) systems.

Publications

The toxin/immunity network of Burkholderia pseudomallei contact-dependent growth inhibition (CDI) systems.

Similar Datasets

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