scholarly journals Contact-dependent growth inhibition tRNase toxin-immunity protein complexes from Escherichia coli 3006 and Klebsiella pneumoniae 342

2019 ◽  
Vol 75 (a1) ◽  
pp. a270-a270
Author(s):  
Karolina Michalska ◽  
William H. Eschenfeldt ◽  
Lucy Stols ◽  
Grant C. Gucinski ◽  
Celia W. Goulding ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Growth Inhibition ◽  
Protein Complexes ◽  
Immunity Protein ◽  
Dependent Growth ◽  
Contact Dependent Growth Inhibition

scholarly journals Contact-Dependent Growth Inhibition Causes Reversible Metabolic Downregulation in Escherichia coli

2009 ◽  
Vol 191 (6) ◽  
pp. 1777-1786 ◽  
Author(s):  
S. K. Aoki ◽  
J. S. Webb ◽  
B. A. Braaten ◽  
D. A. Low
Keyword(s):  
Escherichia Coli ◽  
Growth Inhibition ◽  
Target Cells ◽  
Immunity Protein ◽  
E Coli ◽  
Outer Membranes ◽  
Altered Cell ◽  
Dependent Growth ◽  
Necessary And Sufficient ◽  
Contact Dependent Growth Inhibition

ABSTRACT Contact-dependent growth inhibition (CDI) is a mechanism identified in Escherichia coli by which bacteria expressing two-partner secretion proteins encoded by cdiA and cdiB bind to BamA in the outer membranes of target cells and inhibit their growth. A third gene in the cluster, cdiI, encodes a small protein that is necessary and sufficient to confer immunity to CDI, thereby preventing cells expressing the cdiBA genes from inhibiting their own growth. In this study, the cdiI gene was placed under araBAD promoter control to modulate levels of the immunity protein and thereby induce CDI by removal of arabinose. This CDI autoinhibition system was used for metabolic analyses of a single population of E. coli cells undergoing CDI. Contact-inhibited cells showed altered cell morphology, including the presence of filaments. Notably, CDI was reversible, as evidenced by resumption of cell growth and normal cellular morphology following induction of the CdiI immunity protein. Recovery of cells from CDI also required an energy source. Cells undergoing CDI showed a significant, reversible downregulation of metabolic parameters, including aerobic respiration, proton motive force (Δp), and steady-state ATP levels. It is unclear whether the decrease in respiration and/or Δp is directly involved in growth inhibition, but a role for ATP in the CDI mechanism was ruled out using an atp mutant. Consistent with the observed decrease in Δp, the phage shock response was induced in cells undergoing CDI but not in recovering cells, based on analysis of levels of pspA mRNA.

scholarly journals Diversity of Contact-Dependent Growth Inhibition Systems ofPseudomonas aeruginosa

2019 ◽  
Vol 201 (14) ◽  
Author(s):  
Jonathan P. Allen ◽  
Alan R. Hauser
Keyword(s):  
Growth Inhibition ◽  
Target Cell ◽  
Affinity Binding ◽  
Immunity Protein ◽  
High Affinity Binding ◽  
Content Type ◽  
High Affinity ◽  
Bacterial Competition ◽  
Dependent Growth ◽  
Contact Dependent Growth Inhibition

ABSTRACTContact-dependent growth inhibition (CDI) systems are used in bacterial competition to hinder the growth of neighboring microbes. These systems utilize a two-partner secretion mechanism to display the CdiA exoprotein at the bacterial cell surface. CdiA forms a long filamentous stalk that facilitates binding to a target cell and delivery of a C-terminal toxin (CT) domain. This CT domain is processed and delivered into the cytoplasm of a target cell upon contact. CDI systems also encode a cognate immunity protein (CdiI) that protects siblings and resistant targeted cells from intoxication by high-affinity binding to the CT. CdiA CT domains vary among strains within a species, and many alleles encode enzymatic functions that target nucleic acids. This variation is thought to help drive diversity and adaptation within a species. CdiA diversity is well studied inEscherichia coliand several other bacteria, but little is known about the extent of this diversity inPseudomonas aeruginosa. The purpose of this review is to highlight the variability that exists in CDI systems ofP. aeruginosa. We show that this diversity is apparent even among strains isolated from a single geographical region, suggesting that CDI systems play an important role in the ecology ofP. aeruginosa.

scholarly journals The structure of a contact-dependent growth-inhibition (CDI) immunity protein fromNeisseria meningitidisMC58

2015 ◽  
Vol 71 (6) ◽  
pp. 702-709 ◽  
Author(s):  
Kemin Tan ◽  
Parker M. Johnson ◽  
Lucy Stols ◽  
Bryan Boubion ◽  
William Eschenfeldt ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Effector Proteins ◽  
Binding Motif ◽  
Nucleic Acid Binding ◽  
Immunity Protein ◽  
Docking Simulations ◽  
Dependent Growth ◽  
Contact Dependent Growth Inhibition

Contact-dependent growth inhibition (CDI) is an important mechanism of intercellular competition between neighboring Gram-negative bacteria. CDI systems encode large surface-exposed CdiA effector proteins that carry a variety of C-terminal toxin domains (CdiA-CTs). All CDI+bacteria also produce CdiI immunity proteins that specifically bind to the cognate CdiA-CT and neutralize its toxin activity to prevent auto-inhibition. Here, the X-ray crystal structure of a CdiI immunity protein fromNeisseria meningitidisMC58 is presented at 1.45 Å resolution. The CdiI protein has structural homology to the Whirly family of RNA-binding proteins, but appears to lack the characteristic nucleic acid-binding motif of this family. Sequence homology suggests that the cognate CdiA-CT is related to the eukaryotic EndoU family of RNA-processing enzymes. A homology model is presented of the CdiA-CT based on the structure of the XendoU nuclease fromXenopus laevis. Molecular-docking simulations predict that the CdiA-CT toxin active site is occluded upon binding to the CdiI immunity protein. Together, these observations suggest that the immunity protein neutralizes toxin activity by preventing access to RNA substrates.

scholarly journals Receptor Polymorphism Restricts Contact-Dependent Growth Inhibition to Members of the Same Species

mBio ◽  
2013 ◽  
Vol 4 (4) ◽  
Author(s):  
Zachary C. Ruhe ◽  
Adam B. Wallace ◽  
David A. Low ◽  
Christopher S. Hayes
Keyword(s):  
Escherichia Coli ◽  
Growth Inhibition ◽  
Target Cell ◽  
Bacterial Species ◽  
Target Cells ◽  
Content Type ◽  
E Coli ◽  
Dependent Growth ◽  
Contact Dependent Growth Inhibition

ABSTRACT Bacteria that express contact-dependent growth inhibition (CDI) systems outcompete siblings that lack immunity, suggesting that CDI mediates intercellular competition. To further explore the role of CDI in competition, we determined the target cell range of the CDIEC93 system from Escherichia coli EC93. The CdiAEC93 effector protein recognizes the widely conserved BamA protein as a receptor, yet E. coli EC93 does not inhibit other enterobacterial species. The predicted membrane topology of BamA indicates that three of its extracellular loops vary considerably between species, suggesting that loop heterogeneity may control CDI specificity. Consistent with this hypothesis, other enterobacteria are sensitized to CDIEC93 upon the expression of E. coli bamA and E. coli cells become CDIEC93 resistant when bamA is replaced with alleles from other species. Our data indicate that BamA loops 6 and 7 form the CdiAEC93-binding epitope and their variation between species restricts CDIEC93 target cell selection. Although BamA loops 6 and 7 vary dramatically between species, these regions are identical in hundreds of E. coli strains, suggesting that BamAEcoli and CdiAEC93 play a role in self-nonself discrimination. IMPORTANCE Contact-dependent growth inhibition (CDI) systems are widespread among Gram-negative bacteria, enabling them to bind to neighboring bacterial cells and deliver protein toxins that inhibit cell growth. In this study, we tested the role of CDI in interspecies competition using intestinal isolate Escherichia coli EC93 as an inhibitor cell model. Although E. coli EC93 inhibits different E. coli strains, other bacterial species from the intestine are completely resistant to CDI. We show that resistance is due to small variations in the CDI receptor that prevent other species from being recognized as target cells. CDI receptor interactions thus provide a mechanism by which bacteria can distinguish siblings and other close relatives (self) from more distant relatives or other species of bacteria (nonself). Our results provide a possible means by which antimicrobials could be directed to one or only a few related bacterial pathogens by using a specific receptor “zip code.”

scholarly journals Burkholderia cepacia Complex Contact-Dependent Growth Inhibition Systems Mediate Interbacterial Competition

2019 ◽  
Vol 201 (12) ◽  
Author(s):  
Tanya Myers-Morales ◽  
A. Elizabeth Oates ◽  
Matthew S. Byrd ◽  
Erin C. Garcia
Keyword(s):  
Cystic Fibrosis ◽  
Growth Inhibition ◽  
Burkholderia Cepacia ◽  
Gram Negative Bacteria ◽  
Immunity Protein ◽  
Gram Negative ◽  
Content Type ◽  
Burkholderia Multivorans ◽  
Dependent Growth ◽  
Contact Dependent Growth Inhibition

ABSTRACT 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.

scholarly journals Escherichia coli EC93 deploys two plasmid-encoded class I contact-dependent growth inhibition systems for antagonistic bacterial interactions

2021 ◽  
Author(s):  
Marcus Wäneskog ◽  
Tiffany Halvorsen ◽  
Klara Filek ◽  
Feifei Xu ◽  
Disa L. Hammarlöf ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Inhibition ◽  
Type Species ◽  
Target Cells ◽  
Content Type ◽  
E Coli ◽  
Link Type ◽  
Immunity Genes ◽  
Dependent Growth ◽  
Contact Dependent Growth Inhibition

The phenomenon of contact-dependent growth inhibition (CDI) and the genes required for CDI (cdiBAI) were identified and isolated in 2005 from an Escherichia coli isolate (EC93) from rats. Although the cdiBAI EC93 locus has been the focus of extensive research during the past 15 years, little is known about the EC93 isolate from which it originates. Here we sequenced the EC93 genome and find two complete and functional cdiBAI loci (including the previously identified cdi locus), both carried on a large 127 kb plasmid. These cdiBAI systems are differentially expressed in laboratory media, enabling EC93 to outcompete E. coli cells lacking cognate cdiI immunity genes. The two CDI systems deliver distinct effector peptides that each dissipate the membrane potential of target cells, although the two toxins display different toxic potencies. Despite the differential expression and toxic potencies of these CDI systems, both yielded similar competitive advantages against E. coli cells lacking immunity. This can be explained by the fact that the less expressed cdiBAI system (cdiBAIEC93-2 ) delivers a more potent toxin than the highly expressed cdiBAIEC93-1 system. Moreover, our results indicate that unlike most sequenced CDI+ bacterial isolates, the two cdi loci of E. coli EC93 are located on a plasmid and are expressed in laboratory media.

scholarly journals Identification of Functional Toxin/Immunity Genes Linked to Contact-Dependent Growth Inhibition (CDI) and Rearrangement Hotspot (Rhs) Systems

PLoS Genetics ◽  
2011 ◽  
Vol 7 (8) ◽  
pp. e1002217 ◽  
Author(s):  
Stephen J. Poole ◽  
Elie J. Diner ◽  
Stephanie K. Aoki ◽  
Bruce A. Braaten ◽  
Claire t'Kint de Roodenbeke ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Immunity Genes ◽  
Dependent Growth ◽  
Contact Dependent Growth Inhibition

scholarly journals Structural insight into toxin secretion by contact-dependent growth inhibition transporters

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Jeremy Guerin ◽  
Istvan Botos ◽  
Zijian Zhang ◽  
Karl Lundquist ◽  
James C Gumbart ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Outer Membrane ◽  
Structural Modifications ◽  
Extracellular Loops ◽  
Toxin Secretion ◽  
Dependent Growth ◽  
Α Helix ◽  
Dynamics Simulations ◽  
Outer Membrane Transporters ◽  
Contact Dependent Growth Inhibition

Bacterial contact-dependent growth inhibition (CDI) systems use a type Vb secretion mechanism to export large CdiA toxins across the outer membrane by dedicated outer membrane transporters called CdiB. Here, we report the first crystal structures of two CdiB transporters from Acinetobacter baumannii and Escherichia coli. CdiB transporters adopt a TpsB fold, containing a 16-stranded transmembrane β-barrel connected to two periplasmic domains. The lumen of the CdiB pore is occluded by an N-terminal α-helix and the conserved extracellular loop 6; these two elements adopt different conformations in the structures. We identified a conserved DxxG motif located on strand β1 that connects loop 6 through different networks of interactions. Structural modifications of DxxG induce rearrangement of extracellular loops and alter interactions with the N-terminal α-helix, preparing the system for α-helix ejection. Using structural biology, functional assays, and molecular dynamics simulations, we show how the barrel pore is primed for CdiA toxin secretion.

scholarly journals Genetic Evidence for SecY Translocon-Mediated Import of Two Contact-Dependent Growth Inhibition (CDI) Toxins

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Allison M. Jones ◽  
Petra Virtanen ◽  
Disa Hammarlöf ◽  
William J. Allen ◽  
Ian Collinson ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Target Cell ◽  
Bacterial Species ◽  
Genetic Evidence ◽  
Target Cells ◽  
Content Type ◽  
Sec Translocon ◽  
Dependent Growth ◽  
Cell Envelopes ◽  
Contact Dependent Growth Inhibition

ABSTRACT The C-terminal (CT) toxin domains of contact-dependent growth inhibition (CDI) CdiA proteins target Gram-negative bacteria and must breach both the outer and inner membranes of target cells to exert growth inhibitory activity. Here, we examine two CdiA-CT toxins that exploit the bacterial general protein secretion machinery after delivery into the periplasm. A Ser281Phe amino acid substitution in transmembrane segment 7 of SecY, the universally conserved channel-forming subunit of the Sec translocon, decreases the cytotoxicity of the membrane depolarizing orphan10 toxin from enterohemorrhagic Escherichia coli EC869. Target cells expressing secYS281F and lacking either PpiD or YfgM, two SecY auxiliary factors, are fully protected from CDI-mediated inhibition either by CdiA-CTo10EC869 or by CdiA-CTGN05224, the latter being an EndoU RNase CdiA toxin from Klebsiella aerogenes GN05224 that has a related cytoplasm entry domain. RNase activity of CdiA-CTGN05224 was reduced in secYS281F target cells and absent in secYS281F ΔppiD or secYS281F ΔyfgM target cells during competition co-cultures. Importantly, an allele-specific mutation in secY (secYG313W) renders ΔppiD or ΔyfgM target cells specifically resistant to CdiA-CTGN05224 but not to CdiA-CTo10EC869, further suggesting a direct interaction between SecY and the CDI toxins. Our results provide genetic evidence of a unique confluence between the primary cellular export route for unfolded polypeptides and the import pathways of two CDI toxins. IMPORTANCE Many bacterial species interact via direct cell-to-cell contact using CDI systems, which provide a mechanism to inject toxins that inhibit bacterial growth into one another. Here, we find that two CDI toxins, one that depolarizes membranes and another that degrades RNA, exploit the universally conserved SecY translocon machinery used to export proteins for target cell entry. Mutations in genes coding for members of the Sec translocon render cells resistant to these CDI toxins by blocking their movement into and through target cell membranes. This work lays the foundation for understanding how CDI toxins interact with the protein export machinery and has direct relevance to development of new antibiotics that can penetrate bacterial cell envelopes.

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