AbiEi binds cooperatively to the Type IV abiE toxin-antitoxin operator via a positively-charged surface and causes DNA bending and negative autoregulation

Hampton, H.G.; Jackson, S.A.; Fagerlund, R.D.; Vogel, A.I.M.; Dy, R.L.; Blower, T.R.; Fineran, P.C.

Abstract

Bacteria resist phage infection using multiple strategies, including CRISPR-Cas and abortive infection (Abi) systems. Abi systems provide population-level protection from phage predation, via “altruistic” cell suicide. It has recently been shown that some Abi systems function via a toxin-antitoxin (TA) mechanism, such as the widespread AbiE family. The Streptococcus agalactiae AbiE system consists of a bicistronic operon encoding the AbiEi antitoxin and AbiEii toxin, which function as a Type IV TA system. Here we examine the AbiEi antitoxin, which belongs to a large family of transcriptional regulators with a conserved N-terminal winged-helix-turn-helix (wHTH) domain. This wHTH is essential for transcriptional repression of the abiE operon. The function of the AbiEi C-terminal domain (CTD) is poorly characterised, but it contributes to transcriptional repression and is sufficient for toxin neutralization. We demonstrate that a conserved charged surface on one face of the CTD assists sequence-specific DNA binding and negative autoregulation, without influencing antitoxicity. Furthermore, AbiEi binds cooperatively to two inverted repeats within the abiE promoter and bends the DNA by 72°. These findings demonstrate the mechanism of DNA binding by the widespread family of AbiEi antitoxins and transcriptional regulators can contribute to negative autoregulation.

Citation

Hampton, H., Jackson, S., Fagerlund, R., Vogel, A., Dy, R., Blower, T., & Fineran, P. (2018). AbiEi binds cooperatively to the Type IV abiE toxin-antitoxin operator via a positively-charged surface and causes DNA bending and negative autoregulation. Journal of Molecular Biology, 430(8), 1141-1156. https://doi.org/10.1016/j.jmb.2018.02.022

• Journal Article Type: Article
• Acceptance Date: Feb 25, 2018
• Online Publication Date: Mar 6, 2018
• Publication Date: Apr 1, 2018
• Deposit Date: Mar 6, 2018
• Publicly Available Date: Mar 6, 2019
• Journal: Journal of Molecular Biology
• Print ISSN: 0022-2836
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 430
• Issue: 8
• Pages: 1141-1156
• DOI: https://doi.org/10.1016/j.jmb.2018.02.022
• Public URL: https://durham-repository.worktribe.com/output/1333649