7ZGE

BrxA, BREX phage defence protein

Summary for 7ZGE

• Entry DOI: 10.2210/pdb7zge/pdb
• Descriptor: BrxA, BREX phage defence protein (2 entities in total)
• Functional Keywords: brex phage defence bacteriophage exclusion, antiviral protein
• Biological source: Escherichia fergusonii ATCC 35469
• Total number of polymer chains: 3
• Total formula weight: 68311.21

Authors

Picton, D.M.,Beck, I.N.,Blower, T.R. (deposition date: 2022-04-03, release date: 2022-06-22, Last modification date: 2026-03-11)

Primary citation

Beck, I.N.,Picton, D.M.,Blower, T.R.
Crystal structure of the BREX phage defence protein BrxA.
Curr Res Struct Biol, 4:211-219, 2022

PubMed 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 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.

PubMed: 35783086
DOI: 10.1016/j.crstbi.2022.06.001

Experimental method

X-RAY DIFFRACTION (2.09 Å)