Primary Citation of Related Structures: 6CP8, 6CP9
PubMed 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 ...
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 tRNA GAU Ile . Although the toxins are similar in structure and substrate specificity, CdiA-CT Kp342 activity requires translation factors EF-Tu and EF-Ts, whereas CdiA-CT EC3006 is intrinsically active. Furthermore, the corresponding immunity proteins are unrelated in sequence and structure. CdiI Kp342 forms a dimeric β sandwich, whereas CdiI EC3006 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.
Related Citations:
Target highlights in CASP13: Experimental target structures through the eyes of their authors. Lepore, R., Kryshtafovych, A., Alahuhta, M., Veraszto, H.A., Bomble, Y.J., Bufton, J.C., Bullock, A.N., Caba, C., Cao, H., Davies, O.R., Desfosses, A., Dunne, M., Fidelis, K., Goulding, C.W., Gurusaran, M., Gutsche, I., Harding, C.J., Hartmann, M.D., Hayes, C.S., Joachimiak, A., Leiman, P.G., Loppnau, P., Lovering, A.L., Lunin, V.V., Michalska, K., Mir-Sanchis, I., Mitra, A., Moult, J., Phillips Jr., G.N., Pinkas, D.M., Rice, P.A., Tong, Y., Topf, M., Walton, J.D., Schwede, T. (2019) Proteins --: --
Organizational Affiliation:
Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA; Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA. Electronic address: chayes@lifesci.ucsb.edu.
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