| Literature DB >> 31515004 |
Grant C Gucinski1, Karolina Michalska2, Fernando Garza-Sánchez3, William H Eschenfeldt4, Lucy Stols4, Josephine Y Nguyen3, Celia W Goulding5, Andrzej Joachimiak6, Christopher S Hayes7.
Abstract
Contact-dependent growth inhibition (CDI) is a form of interbacterial competition mediated by CdiB-CdiA two-partner secretion systems. CdiA effector proteins carry polymorphic C-terminal toxin domains (CdiA-CT), which are neutralized by specific CdiI immunity proteins to prevent self-inhibition. Here, we present the crystal structures of CdiA-CT⋅CdiI complexes from Klebsiella pneumoniae 342 and Escherichia coli 3006. The toxins adopt related folds that resemble the ribonuclease domain of colicin D, and both are isoacceptor-specific tRNases that cleave the acceptor stem of deacylated tRNAGAUIle. Although the toxins are similar in structure and substrate specificity, CdiA-CTKp342 activity requires translation factors EF-Tu and EF-Ts, whereas CdiA-CTEC3006 is intrinsically active. Furthermore, the corresponding immunity proteins are unrelated in sequence and structure. CdiIKp342 forms a dimeric β sandwich, whereas CdiIEC3006 is an α-solenoid monomer. Given that toxin-immunity genes co-evolve as linked pairs, these observations suggest that the similarities in toxin structure and activity reflect functional convergence.Entities:
Keywords: bacterial competition; toxin-antitoxin systems; two-partner secretion; type V secretion system
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Year: 2019 PMID： 31515004 PMCID： PMC6834915 DOI： 10.1016/j.str.2019.08.010
Source DB: PubMed Journal: Structure ISSN： 0969-2126 Impact factor: 5.006