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: 2024-03-20)

Primary citation

Usher, B.,Birkholz, N.,Beck, I.N.,Fagerlund, R.D.,Jackson, S.A.,Fineran, P.C.,Blower, T.R.
Crystal structure of the anti-CRISPR repressor Aca2.
J.Struct.Biol., 213:107752-107752, 2021

PubMed Abstract: Bacteria use adaptive CRISPR-Cas immune mechanisms to protect from invasion by bacteriophages and other mobile genetic elements. In response, bacteriophages and mobile genetic elements have co-evolved anti-CRISPR proteins to inhibit the bacterial defense. We and others have previously shown that anti-CRISPR associated (Aca) proteins can regulate this anti-CRISPR counter-attack. Here, we report the first structure of an Aca protein, the Aca2 DNA-binding transcriptional autorepressor from Pectobacterium carotovorum bacteriophage ZF40, determined to 1.34 Å. Aca2 presents a conserved N-terminal helix-turn-helix DNA-binding domain and a previously uncharacterized C-terminal dimerization domain. Dimerization positions the Aca2 recognition helices for insertion into the major grooves of target DNA, supporting its role in regulating anti-CRISPRs. Furthermore, database comparisons identified uncharacterized Aca2 structural homologs in pathogenic bacteria, suggesting that Aca2 represents the first characterized member of a more widespread family of transcriptional regulators.

PubMed: 34116143
DOI: 10.1016/j.jsb.2021.107752

Experimental method

X-RAY DIFFRACTION (2.09 Å)