Anti-CRISPR-Associated Proteins Are Crucial Repressors of Anti-CRISPR Transcription

Sabrina Y Stanley; Adair L Borges; Kuei-Ho Chen; Danielle L Swaney; Nevan J Krogan; Joseph Bondy-Denomy; Alan R Davidson

doi:10.1016/j.cell.2019.07.046

Anti-CRISPR-Associated Proteins Are Crucial Repressors of Anti-CRISPR Transcription

Cell. 2019 Sep 5;178(6):1452-1464.e13. doi: 10.1016/j.cell.2019.07.046. Epub 2019 Aug 29.

Authors

Sabrina Y Stanley¹, Adair L Borges², Kuei-Ho Chen³, Danielle L Swaney⁴, Nevan J Krogan⁴, Joseph Bondy-Denomy⁵, Alan R Davidson⁶

Affiliations

¹ Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada.
² Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA.
³ The J. David Gladstone Institutes, San Francisco, CA 94158 USA.
⁴ The J. David Gladstone Institutes, San Francisco, CA 94158 USA; Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA.
⁵ Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA; Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94143, USA.
⁶ Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada. Electronic address: alan.davidson@utoronto.ca.

Abstract

Phages express anti-CRISPR (Acr) proteins to inhibit CRISPR-Cas systems that would otherwise destroy their genomes. Most acr genes are located adjacent to anti-CRISPR-associated (aca) genes, which encode proteins with a helix-turn-helix DNA-binding motif. The conservation of aca genes has served as a signpost for the identification of acr genes, but the function of the proteins encoded by these genes has not been investigated. Here we reveal that an acr-associated promoter drives high levels of acr transcription immediately after phage DNA injection and that Aca proteins subsequently repress this transcription. Without Aca activity, this strong transcription is lethal to a phage. Our results demonstrate how sufficient levels of Acr proteins accumulate early in the infection process to inhibit existing CRISPR-Cas complexes in the host cell. They also imply that the conserved role of Aca proteins is to mitigate the deleterious effects of strong constitutive transcription from acr promoters.

Keywords: CRISPR-Cas; Horizontal gene transfer; Phage; Pseudomonas aeruginosa; Transcriptional regulator; anti-CRISPR.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Bacteriophages / genetics*
CRISPR-Associated Proteins / genetics
CRISPR-Cas Systems / genetics*
Clustered Regularly Interspaced Short Palindromic Repeats / genetics*
Escherichia coli / virology
Promoter Regions, Genetic / genetics
Pseudomonas aeruginosa / virology
Transcription Factors / genetics
Transcription, Genetic
Viral Proteins / genetics*

Substances

CRISPR-Associated Proteins
Transcription Factors
Viral Proteins

Abstract

Publication types

MeSH terms

Substances

Grants and funding