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Crystal structure of the anti-CRISPR repressor Aca2

DOI: 10.1016/j.jsb.2021.107752 DOI Help

Authors: Ben Usher (Durham University) , Nils Birkholz (University of Otago) , Izaak N. Beck (Durham University) , Robert D. Fagerlund (University of Otago) , Simon A. Jackson (University of Otago) , Peter C. Fineran (University of Otago) , Tim R. Blower (Durham University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Structural Biology , VOL 213

State: Published (Approved)
Published: September 2021
Diamond Proposal Number(s): 24948

Open Access Open Access

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.

Journal Keywords: CRISPR; X-ray crystallography; Anti-CRISPR associated; Transcriptional regulator; Aca2

Diamond Keywords: Bacteria

Subject Areas: Biology and Bio-materials


Instruments: I04-Macromolecular Crystallography

Documents:
1-s2.0-S1047847721000575-main.pdf

Discipline Tags:

Genetics Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)