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Publication Abstract from PubMed

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 from Neisseria meningitidis MC58 is presented at 1.45 A 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 from Xenopus 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.

The structure of a contact-dependent growth-inhibition (CDI) immunity protein from Neisseria meningitidis MC58.,Tan K, Johnson PM, Stols L, Boubion B, Eschenfeldt W, Babnigg G, Hayes CS, Joachimiak A, Goulding CW Acta Crystallogr F Struct Biol Commun. 2015 Jun 1;71(Pt 6):702-9. doi:, 10.1107/S2053230X15006585. Epub 2015 May 20. PMID:26057799^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.