EMD-50028
Focused map for NTD and MTD domains of the phage immunity methyltransferase protein BrxX.
EMD-50028
Single-particle2.84 Å
Deposition: 05/04/2024Map released: 05/03/2025
Last modified: 05/03/2025
Sample Organism:
Escherichia coli
Sample: N-terminal domain (NTD) and methyltransferase domain (MTD) from BrxX
Deposition Authors: Adams MC, Ghilarov D
Sample: N-terminal domain (NTD) and methyltransferase domain (MTD) from BrxX
Deposition Authors: Adams MC, Ghilarov D
Molecular basis of foreign DNA recognition by BREX anti-phage immunity system.
Drobiazko A,
Adams MC,
Skutel M,
Potekhina K,
Kotovskaya O,
Trofimova A,
Matlashov M,
Yatselenko D,
Maxwell KL,
Blower TR,
Severinov K,
Ghilarov D,
Isaev A
(2025) Nat Commun , 16 , 1825 - 1825
(2025) Nat Commun , 16 , 1825 - 1825
Abstract:
Anti-phage systems of the BREX (BacteRiophage EXclusion) superfamily rely on site-specific epigenetic DNA methylation to discriminate between the host and invading DNA. We demonstrate that in Type I BREX systems, defense and methylation require BREX site DNA binding by the BrxX (PglX) methyltransferase employing S-adenosyl methionine as a cofactor. We determined 2.2-Å cryoEM structure of Escherichia coli BrxX bound to target dsDNA revealing molecular details of BREX DNA recognition. Structure-guided engineering of BrxX expands its DNA specificity and dramatically enhances phage defense. We show that BrxX alone does not methylate DNA, and BREX activity requires an assembly of a supramolecular BrxBCXZ immune complex. Finally, we present a cryoEM structure of BrxX bound to a phage-encoded inhibitor Ocr that sequesters BrxX in an inactive dimeric form. We propose that BrxX-mediated foreign DNA sensing is a necessary first step in activation of BREX defense.
Anti-phage systems of the BREX (BacteRiophage EXclusion) superfamily rely on site-specific epigenetic DNA methylation to discriminate between the host and invading DNA. We demonstrate that in Type I BREX systems, defense and methylation require BREX site DNA binding by the BrxX (PglX) methyltransferase employing S-adenosyl methionine as a cofactor. We determined 2.2-Å cryoEM structure of Escherichia coli BrxX bound to target dsDNA revealing molecular details of BREX DNA recognition. Structure-guided engineering of BrxX expands its DNA specificity and dramatically enhances phage defense. We show that BrxX alone does not methylate DNA, and BREX activity requires an assembly of a supramolecular BrxBCXZ immune complex. Finally, we present a cryoEM structure of BrxX bound to a phage-encoded inhibitor Ocr that sequesters BrxX in an inactive dimeric form. We propose that BrxX-mediated foreign DNA sensing is a necessary first step in activation of BREX defense.