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Crystal structure of the BREX phage defence protein BrxA

Beck, I.N.; Picton, D.M.; Blower, T.R.

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Authors

Izaak Beck izaak.beck@durham.ac.uk
PGR Student Doctor of Philosophy

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David Picton david.m.picton@durham.ac.uk
PGR Student Doctor of Philosophy



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.

Citation

Beck, I., Picton, D., & Blower, T. (2022). Crystal structure of the BREX phage defence protein BrxA. Current Research in Structural Biology, https://doi.org/10.1016/j.crstbi.2022.06.001

Journal Article Type Article
Acceptance Date Jun 1, 2022
Online Publication Date Jun 8, 2022
Publication Date 2022
Deposit Date Jun 22, 2022
Publicly Available Date Mar 29, 2024
Journal Current Research in Structural Biology
Publisher Elsevier
Peer Reviewed Peer Reviewed
DOI https://doi.org/10.1016/j.crstbi.2022.06.001

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