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Crystal structure of the BREX phage defence protein BrxA

DOI: 10.1016/j.crstbi.2022.06.001 DOI Help

Authors: Izaak N. Beck (Durham University) , David M. Picton (Durham University) , Tim R. Blower (Durham University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Current Research In Structural Biology , VOL 66

State: Published (Approved)
Published: June 2022
Diamond Proposal Number(s): 24948

Open Access Open Access

Abstract: Bacteria are constantly challenged by bacteriophage (phage) infection and have developed multitudinous and varied resistance mechanisms. Bacteriophage Exclusion (BREX) systems protect from phage infection by generating methylation patterns at non-palindromic 6 bp sites in host bacterial DNA, to distinguish and block replication of non-self DNA. Type 1 BREX systems are comprised of six conserved core genes. Here, we present the first reported structure of a BREX core protein, BrxA from the phage defence island of Escherichia fergusonii ATCC 35469 plasmid pEFER, solved to 2.09 Å. BrxA is a monomeric protein in solution, with an all α-helical globular fold. Conservation of surface charges and structural homology modelling against known phage defence systems highlighted that BrxA contains two helix-turn-helix motifs, juxtaposed by 180°, positioned to bind opposite sides of a DNA major groove. BrxA was subsequently shown to bind dsDNA. This new understanding of BrxA structure, and first indication of BrxA biological activity, suggests a conserved mode of DNA-recognition has become widespread and implemented by diverse phage defence systems.

Diamond Keywords: Bacteria

Subject Areas: Biology and Bio-materials

Instruments: I24-Microfocus Macromolecular Crystallography

Added On: 09/06/2022 11:27


Discipline Tags:

Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)