Dynamics and evolution of specificity of TA complexes

TA dynamics

Toxin-antitoxin (TA) systems are ubiquitous genetic modules promoting bacterial survival by regulation and arrest of cell growth in response to stresses such as phage infection, antibiotic exposure, or macrophage uptake. While toxins target essential biological processes affecting growth of a cell, antitoxins specifically neutralize their cognate toxins and allow for cell growth. In the most prevalent type II TAs, the antitoxin is a protein that directly binds its cognate toxin with a neutralization domain (ND), resulting in formation of a tight toxin-antitoxin complex. Besides the ND, the antitoxin also contains a DNA binding domain enabling it to transcriptionally control the toxin-antitoxin operon. Another key feature of TAs is the common presence of several paralogues of the same system within the same organism. The frequent complete insulation of numerous paralogous TAs, where there is high specificity with no cross-pairing, suggests that a neutralizing cross-interaction is detrimental to the cell. We are interested in studying the evolution of specificity of paralogous TA systems through toxin size variation by addition of structural add-on elements then allowing the antitoxin to evolve a specific neutralizing sequence. We found that such size alteration occurs at either N- or C-terminal toxin ends in various TA systems. Building on the experience gained while studying three paralogous Salmonella TacAT1-3 TA systems, we will continue to explore the significance of add-ons in contribution to development of neutralization specificity reducing paralogue crosstalk conflict. We will also investigate the activation of an important family of TAs involved in persistence of pathogenic Salmonella. Overall, these studies will provide new insights into the dynamics of evolution of paralogous protein-protein complexes and protein-DNA complexes, thereby opening avenues of interfering with these important stress response elements in bacteria.


Structures of S. enterica TacT1-3 toxins neutralized by their cognate TacA1-3 antitoxins.
Green color points to the variable TacT C-terminal add-on.

Grzegorz J. Grabe, PhD – Principal Investigator
Structural Biology Laboratory
phone: +48 58 523 6434


           2016 – PhD, Imperial College London, UK
           2011 – MRes, Imperial College London, UK
           2010 – MSc, University of Gdansk and Medical University of Gdansk, Poland
           2007 – BSc, University of Gdansk and Medical University of Gdansk, Poland

Selected publications:

  1. De Castro GV, Worm DJ, Grabe GJ, Rowan FC, Haggerty L, De La Lastra AL, Popescu O, Helaine S & Barnard A. Characterization of the Key Determinants of Phd Antitoxin Mediated Doc Toxin Inactivation in Salmonella. ACS Chem Biol 2022
  2. Grabe GJ, Giorgio RT, Hall AMJ, Morgan RML, Dubois L, Sisley TA, Rycroft JA, Hare SA, Helaine S. Auxiliary interfaces support the evolution of specific toxin–antitoxin pairing. Nat Chem Biol, 2021
  3. Matthews-Palmer TRS, Gonzalez-Rodriguez N, Calcraft T, Lagercrantz S, Zachs T, Yu XJ, Grabe GJ, Holden DW, Nans A, Rosenthal PB, et al. Structure of the cytoplasmic domain of SctV (SsaV) from the Salmonella SPI-2 injectisome and implications for a pH sensing mechanism. J Struct Biol, 2021
  4. Rycroft JA, Gollan B, Grabe GJ, Hall AMJ, Cheverton AM, Larrouy-Maumus G, Hare SA, Helaine S. Activity of acetyltransferase toxins involved in Salmonella persister formation during macrophage infection. Nature Commun, 2018
  5. Yu X-J, Grabe GJ, Liu M, Mota LJ & Holden DW. SsaV interacts with SsaL to control the translocon-to-effector switch in the Salmonella SPI-2 type three secretion system. MBio, 2018
  6. Grabe GJ, Zhang Y, Przydacz M, Rolhion N, Yang Y, Pruneda JN, Komander D, Holden DW & Hare SA. The Salmonella effector SpvD is a cysteine hydrolase with a serovar-specific polymorphism influencing catalytic activity, suppression of immune responses, and bacterial virulence. J Biol Chem, 2016
  7. Rolhion N, Furniss RCD, Grabe GJ, Ryan A, Liu M, Matthews SA & Holden DW. Inhibition of Nuclear Transport of NF-ĸB p65 by the Salmonella Type III Secretion System Effector SpvD. PLoS Pathog, 2016

This research is performed in a Structural Biology Group lead by Prof. Michal Szymanski. The group studies large macromolecular machines involved in DNA replication and repair processes and is located at Intercollegiate Faculty of Biotechnology in Gdansk.

This research is part of the project No. 2022/45/P/NZ1/03666 co-funded by the National Science Centre and the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 945339.



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Data publikacji: czwartek, 2 Marzec, 2023 - 13:27; osoba wprowadzająca: Maria Maja Pega Ostatnia zmiana: środa, 8 Marzec, 2023 - 07:54; osoba wprowadzająca: Maria Maja Pega