| Structural highlights
Function
CDIB_ECOLX Potential outer membrane protein component of a toxin-immunity protein module, which functions as a cellular contact-dependent growth inhibition (CDI) system. CDI modules allow bacteria to communicate with and inhibit the growth of closely related neighboring bacteria in a contact-dependent fashion. This protein may be required for secretion and assembly of the CdiA toxin protein. Inhibitory cells must be in logarithmic (not stationary) phase to inhibit growth of their targets, while the presence of P or S but not type 1 pili protects the target cells against growth inhibition.[1] [2] [3] Probable member of a two partner secretion pathway (TPS) in which it mediates the secretion of CdiA.[4]
Publication Abstract from PubMed
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 beta-barrel connected to two periplasmic domains. The lumen of the CdiB pore is occluded by an N-terminal alpha-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 beta1 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 alpha-helix, preparing the system for alpha-helix ejection. Using structural biology, functional assays, and molecular dynamics simulations, we show how the barrel pore is primed for CdiA toxin secretion.
Structural insight into toxin secretion by contact dependent growth inhibition transporters.,Guerin J, Botos I, Zhang Z, Lundquist K, Gumbart JC, Buchanan SK Elife. 2020 Oct 22;9. pii: 58100. doi: 10.7554/eLife.58100. PMID:33089781[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Aoki SK, Pamma R, Hernday AD, Bickham JE, Braaten BA, Low DA. Contact-dependent inhibition of growth in Escherichia coli. Science. 2005 Aug 19;309(5738):1245-8. PMID:16109881 doi:10.1126/science.1115109
- ↑ Aoki SK, Webb JS, Braaten BA, Low DA. Contact-dependent growth inhibition causes reversible metabolic downregulation in Escherichia coli. J Bacteriol. 2009 Mar;191(6):1777-86. PMID:19124575 doi:10.1128/JB.01437-08
- ↑ Aoki SK, Diner EJ, de Roodenbeke CT, Burgess BR, Poole SJ, Braaten BA, Jones AM, Webb JS, Hayes CS, Cotter PA, Low DA. A widespread family of polymorphic contact-dependent toxin delivery systems in bacteria. Nature. 2010 Nov 18;468(7322):439-42. doi: 10.1038/nature09490. PMID:21085179 doi:http://dx.doi.org/10.1038/nature09490
- ↑ Aoki SK, Pamma R, Hernday AD, Bickham JE, Braaten BA, Low DA. Contact-dependent inhibition of growth in Escherichia coli. Science. 2005 Aug 19;309(5738):1245-8. PMID:16109881 doi:10.1126/science.1115109
- ↑ Guerin J, Botos I, Zhang Z, Lundquist K, Gumbart JC, Buchanan SK. Structural insight into toxin secretion by contact-dependent growth inhibition transporters. Elife. 2020 Oct 22;9:e58100. PMID:33089781 doi:10.7554/eLife.58100
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