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Crystal structure of the anti-CRISPR repressor Aca2

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 Thumbnail


Authors

B. Usher

N. Birkholz

I.N. Beck

R.D. Fagerlund

S.A. Jackson

P.C. Fineran



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.

Citation

Usher, B., Birkholz, N., Beck, I., Fagerlund, R., Jackson, S., Fineran, P., & Blower, T. (2021). Crystal structure of the anti-CRISPR repressor Aca2. Journal of Structural Biology, 213(3), Article 107752. https://doi.org/10.1016/j.jsb.2021.107752

Journal Article Type Article
Acceptance Date Jun 6, 2021
Online Publication Date Jun 8, 2021
Publication Date 2021-09
Deposit Date Jun 7, 2021
Publicly Available Date Mar 28, 2024
Journal Journal of Structural Biology
Print ISSN 1047-8477
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 213
Issue 3
Article Number 107752
DOI https://doi.org/10.1016/j.jsb.2021.107752

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