Dataset Information

Broad-spectrum enzymatic inhibition of CRISPR-Cas12a.

ABSTRACT: Cas12a is a bacterial RNA-guided nuclease used widely for genome editing and, more recently, as a molecular diagnostic. In bacteria, Cas12a enzymes can be inhibited by bacteriophage-derived proteins, anti-CRISPRs (Acrs), to thwart clustered regularly interspaced short palindromic repeat (CRISPR) adaptive immune systems. How these inhibitors disable Cas12a by preventing programmed DNA cleavage is unknown. We show that three such inhibitors (AcrVA1, AcrVA4 and AcrVA5) block Cas12a activity via functionally distinct mechanisms, including a previously unobserved enzymatic strategy. AcrVA4 and AcrVA5 inhibit recognition of double-stranded DNA (dsDNA), with AcrVA4 driving dimerization of Cas12a. In contrast, AcrVA1 is a multiple-turnover inhibitor that triggers cleavage of the target-recognition sequence of the Cas12a-bound guide RNA to irreversibly inactivate the Cas12a complex. These distinct mechanisms equip bacteriophages with tools to evade CRISPR-Cas12a and support biotechnological applications for which multiple-turnover enzymatic inhibition of Cas12a is desirable.

SUBMITTER: Knott GJ

PROVIDER: S-EPMC6449189 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Broad-spectrum enzymatic inhibition of CRISPR-Cas12a.

Knott Gavin J GJ Thornton Brittney W BW Lobba Marco J MJ Liu Jun-Jie JJ Al-Shayeb Basem B Watters Kyle E KE Doudna Jennifer A JA

Nature structural & molecular biology 20190401 4

Cas12a is a bacterial RNA-guided nuclease used widely for genome editing and, more recently, as a molecular diagnostic. In bacteria, Cas12a enzymes can be inhibited by bacteriophage-derived proteins, anti-CRISPRs (Acrs), to thwart clustered regularly interspaced short palindromic repeat (CRISPR) adaptive immune systems. How these inhibitors disable Cas12a by preventing programmed DNA cleavage is unknown. We show that three such inhibitors (AcrVA1, AcrVA4 and AcrVA5) block Cas12a activity via fun ...[more]

PMID: 30936531

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Project description:The continuous and rapid surge of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with high transmissibility and evading neutralization is alarming, necessitating expeditious detection of the variants concerned. Here, we report the development of rapid SARS-CoV-2 variants enzymatic detection (SAVED) based on CRISPR-Cas12a targeting of previously crucial variants, including Alpha, Beta, Gamma, Delta, Lambda, Mu, Kappa, and currently circulating variant of concern (VOC) Omicron and its subvariants BA.1, BA.2, BA.3, BA.4, and BA.5. SAVED is inexpensive (US$3.23 per reaction) and instrument-free. SAVED results can be read out by fluorescence reader and tube visualization under UV/blue light, and it is stable for 1 h, enabling high-throughput screening and point-of-care testing. We validated SAVED performance on clinical samples with 100% specificity in all samples and 100% sensitivity for the current pandemic Omicron variant samples having a threshold cycle (CT) value of ≤34.9. We utilized chimeric CRISPR RNA (crRNA) and short crRNA (15-nucleotide [nt] to 17-nt spacer) to achieve single nucleotide polymorphism (SNP) genotyping, which is necessary for variant differentiation and is a challenge to accomplish using CRISPR-Cas12a technology. We propose a scheme that can be used for discriminating variants effortlessly and allows for modifications to incorporate newer upcoming variants as the mutation site of these variants may reappear in future variants. IMPORTANCE Rapid differentiation and detection tests that can directly identify SARS-CoV-2 variants must be developed in order to meet the demands of public health or clinical decisions. This will allow for the prompt treatment or isolation of infected people and the implementation of various quarantine measures for those exposed. We report the development of the rapid SARS-CoV-2 variants enzymatic detection (SAVED) method based on CRISPR-Cas12a that targets previously significant variants like Alpha, Beta, Gamma, Delta, Lambda, Mu, and Kappa as well as the VOC Omicron and its subvariants BA.1, BA.2, BA.3, BA.4, and BA.5 that are currently circulating. SAVED uses no sophisticated instruments and is reasonably priced ($3.23 per reaction). As the mutation location of these variations may reoccur in subsequent variants, we offer a system that can be applied for variant discrimination with ease and allows for adjustments to integrate newer incoming variants.

Dataset Information

Broad-spectrum enzymatic inhibition of CRISPR-Cas12a.

Publications

Broad-spectrum enzymatic inhibition of CRISPR-Cas12a.

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