Structures and Strategies of Anti-CRISPR-Mediated Immune Suppression

Wiegand, Tanner; Karambelkar, Shweta; Bondy‐Denomy, Joseph; Wiedenheft, Blake

doi:10.1146/annurev-micro-020518-120107

Cited by 65 publications

(60 citation statements)

References 98 publications

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“…Self-targeting spacers have been identified in the work of others and have even been used as a tool to help identify anti-CRISPR systems (Borges et al, 2017). However, established members of anti-CRISPR systems are not widely conserved in elements with Tn7-CRISPR-Cas systems in our analysis (Wiegand et al, 2020).…”

Section: Salmonicida S44mentioning

confidence: 83%

Guide RNA categorization enables target site choice in Tn7-CRISPR-Cas transposons

Petassi

Hsieh

Peters

2020

Preprint

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SummaryCRISPR-Cas defense systems have been coopted multiple times in nature for guide RNA-directed transposition by Tn7-like elements. Prototypic Tn7 uses dedicated proteins for two targeting pathways, one targeting a neutral and conserved attachment site in the chromosome and a second directing transposition into mobile plasmids facilitating cell-to-cell transfer. We show that Tn7-CRISPR-Cas elements evolved a system of guide RNA categorization to accomplish the same two-pathway lifestyle. Selective regulation of specialized guide RNAs allows long-term memory for access to chromosomal sites upon entry into a new host, while conventional CRISPR features maintain the ability to continually acquire guide RNAs to new plasmid and phage targets. Transposon-encoded guide RNAs are also privatized to be recognized only by the transposon-adapted system working with selective regulation to guard against toxic self-targeting by endogenous CRISPR-Cas defense systems. This information reveals new avenues to engineer guide RNAs for enhanced CRISPR-Cas functionality for genome modification.

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Section: Salmonicida S44mentioning

confidence: 83%

Guide RNA categorization enables target site choice in Tn7-CRISPR-Cas transposons

Petassi

Hsieh

Peters

2020

Preprint

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“…Our working hypothesis is that these small tailed phages have not been isolated because they are relatively low in abundance in most environments sampled. Larger tailed phage capsids capable of storing longer genomes may have been favored by incorporating genes that can alter the host's physiology, protect the bacterial host against other phages, and overcome the host's resistance mechanisms [6,[33][34][35]. Here, we applied modeling and bioinformatics to narrow the search for small tailed phages, overcoming the current limitations of sampling.…”

Section: Introductionmentioning

confidence: 99%

The Missing Tailed Phages: Prediction of Small Capsid Candidates

Luque

Benler

Lee

et al. 2020

Preprint

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Tailed phages are the most abundant and diverse group of viruses on the planet. Yet, the smallest tailed phages display relatively complex capsids and large genomes compared to other viruses. The lack of tailed phages forming the common icosahedral capsid architectures T = 1 and T = 3 is puzzling. Here, we extracted geometrical features from high-resolution tailed phage capsid reconstructions and built a statistical model based on physical principles to predict the capsid diameter and genome length of the missing small tailed phage capsids. We applied the model to 3,348 isolated tailed phage genomes and 1,496 gut metagenome-assembled tailed phage genomes. Four isolated tailed phages were predicted to form T = 3 icosahedral capsids, and twenty-one metagenome-assembled tailed phages were predicted to form T < 3 capsids. The smallest capsid predicted was a T = 4/3 ≈ 1.33 architecture. No tailed phages were predicted to form the smallest icosahedral architecture, T = 1. We discuss the feasibility of the missing T = 1 tailed phage capsids and the implications of isolating and characterizing small tailed phages for viral evolution and phage therapy.

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“…Type I and type V-A anti-CRISPR proteins carry out their action mainly by preventing Cascade/Cas12a-crRNA complex from recognizing and binding the target DNA or by abolishing DNA cleavage after inactivating the Cas effector. However, enzymatic behaviors have been reported too (Davidson et al, 2020;Wiegand et al, 2020).…”

Section: A Summary Of Anti-crispr Working Mechanismsmentioning

confidence: 99%

Types I and V Anti-CRISPR Proteins: From Phage Defense to Eukaryotic Synthetic Gene Circuits

Marchisio

2020

Front. Bioeng. Biotechnol.

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Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas (CRISPRassociated proteins), a prokaryotic RNA-mediated adaptive immune system, has been repurposed for gene editing and synthetic gene circuit construction both in bacterial and eukaryotic cells. In the last years, the emergence of the anti-CRISPR proteins (Acrs), which are natural OFF-switches for CRISPR-Cas, has provided a new means to control CRISPR-Cas activity and promoted a further development of CRISPR-Cas-based biotechnological toolkits. In this review, we focus on type I and type V-A anti-CRISPR proteins. We first narrate Acrs discovery and analyze their inhibitory mechanisms from a structural perspective. Then, we describe their applications in gene editing and transcription regulation. Finally, we discuss the potential future usageand corresponding possible challenges-of these two kinds of anti-CRISPR proteins in eukaryotic synthetic gene circuits.

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Structures and Strategies of Anti-CRISPR-Mediated Immune Suppression

Cited by 65 publications

References 98 publications

Guide RNA categorization enables target site choice in Tn7-CRISPR-Cas transposons

Guide RNA categorization enables target site choice in Tn7-CRISPR-Cas transposons

The Missing Tailed Phages: Prediction of Small Capsid Candidates

Types I and V Anti-CRISPR Proteins: From Phage Defense to Eukaryotic Synthetic Gene Circuits

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