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Chuan Dong, Ge-Fei Hao, Hong-Li Hua, Shuo Liu, Abraham Alemayehu Labena, Guoshi Chai, Jian Huang, Nini Rao, Feng-Biao Guo
CRISPR-Cas is a tool that is widely used for gene editing. However, unexpected off-target effects may occur as a result of long-term nuclease activity. Anti-CRISPR proteins, which are powerful molecules that inhibit the CRISPR-Cas system, may have the potential to promote better utilization of the CRISPR-Cas system in gene editing, especially for gene therapy. Additionally, more in-depth research on these proteins would help researchers to better understand the co-evolution of bacteria and phages. Therefore, it is necessary to collect and integrate data on various types of anti-CRISPRs...
September 25, 2017: Nucleic Acids Research
Masami Shiimori, Sandra C Garrett, Dwain P Chambers, Claiborne V C Glover, Brenton R Graveley, Michael P Terns
To acquire CRISPR-Cas immunity against invasive mobile genetic elements, prokaryotes must first integrate fragments of foreign DNA into their genomic CRISPR arrays for use in future invader silencing. Here, we found that the hyperthermophilic archaeaon, Pyrococcus furiosus, actively incorporates DNA fragments (spacers) from both plasmid (foreign) and host genome (self) sequences into its seven CRISPR loci. The majority of new spacers were derived from DNA immediately downstream from a 5'-CCN-3' protospacer adjacent motif (PAM) that is critical for invader targeting...
September 25, 2017: Nucleic Acids Research
Stefano Stella, Pablo Alcón, Guillermo Montoya
CRISPR-Cas is a bacterial defense system against phage infection and nucleic acid invasion. Class 2 type II CRISPR-Cas9 has also been widely used for genome engineering. Here, we review novel insights into the CRISPR class 2 type V enzymes, specifically Cpf1 and C2c1, which display different DNA-recognition and cleavage characteristics than those of Cas9, the best-characterized member of class 2. Recent structures of these ribonucleoprotein complexes that capture several stages of the endonuclease reaction have provided molecular details of recognition, unzipping and cleavage of the target DNA, allowing their comparison with Cas9...
October 16, 2017: Nature Structural & Molecular Biology
Pauline Ogrodzki, Stephen J Forsythe
The Cronobacter genus is composed of seven species, within which a number of pathovars have been described. The most notable infections by Cronobacter spp. are of infants through the consumption of contaminated infant formula. The description of the genus has greatly improved in recent years through DNA sequencing techniques, and this has led to a robust means of identification. However some species are highly clonal and this limits the ability to discriminate between unrelated strains by some methods of genotyping...
2017: Frontiers in Microbiology
Claudio Hidalgo-Cantabrana, Alexandra B Crawley, Borja Sanchez, Rodolphe Barrangou
Diverse CRISPR-Cas systems provide adaptive immunity in many bacteria and most archaea, via a DNA-encoded, RNA-mediated, nucleic-acid targeting mechanism. Over time, CRISPR loci expand via iterative uptake of invasive DNA sequences into the CRISPR array during the adaptation process. These genetic vaccination cards thus provide insights into the exposure of strains to phages and plasmids in space and time, revealing the historical predatory exposure of a strain. These genetic loci thus constitute a unique basis for genotyping of strains, with potential of resolution at the strain-level...
2017: Frontiers in Microbiology
Junko Tomida, Yuji Morita, Keigo Shibayama, Ken Kikuchi, Tomohiro Sawa, Takaaki Akaike, Yoshiaki Kawamura
Helicobacter cinaedi is associated with nosocomial infections. The CRISPR-Cas system provides adaptive immunity against foreign genetic elements. We investigated the CRISPR-Cas system in H. cinaedi to assess the potential of the CRISPR-based microevolution of H. cinaedi strains. A genotyping method based on CRISPR spacer organization was carried out using 42 H. cinaedi strains. The results of sequence analysis showed that the H. cinaedi strains used in this study had two CRISPR loci (CRISPR1 and CRISPR2). The lengths of the consensus direct repeat sequences in CRISPR1 and CRISPR2 were both 36 bp-long, and 224 spacers were found in the 42 H...
2017: PloS One
Ianis G Matsoukas
No abstract text is available yet for this article.
2017: Frontiers in Bioengineering and Biotechnology
Kevin Anthony Meyer, Timothy W Davis, Susan B Watson, Vincent J Denef, Michelle A Berry, Gregory J Dick
Blooms of the potentially toxic cyanobacterium Microcystis are increasing worldwide. In the Laurentian Great Lakes they pose major socioeconomic, ecological, and human health threats, particularly in western Lake Erie. However, the interpretation of "omics" data is constrained by the highly variable genome of Microcystis and the small number of reference genome sequences from strains isolated from the Great Lakes. To address this, we sequenced two Microcystis isolates from Lake Erie (Microcystis aeruginosa LE3 and M...
2017: PloS One
Ramona F Kratzer, Florian Kreppel
Vectors based on human adenovirus are highly efficient tools for transient genetic modifications of cells or tissues in vitro and in vivo. They can be utilized for gene addition strategies, knockdown strategies and as transfer vectors for designer nucleases and CRISPR/Cas. They are characterized by high genomic stability and can be produced to high titers. This chapter describes the method how to produce, purify and titrate adenovirus vectors based on human adenovirus type 5.
2017: Methods in Molecular Biology
Tai Wei Guo, Alberto Bartesaghi, Hui Yang, Veronica Falconieri, Prashant Rao, Alan Merk, Edward T Eng, Ashleigh M Raczkowski, Tara Fox, Lesley A Earl, Dinshaw J Patel, Sriram Subramaniam
Prokaryotic cells possess CRISPR-mediated adaptive immune systems that protect them from foreign genetic elements, such as invading viruses. A central element of this immune system is an RNA-guided surveillance complex capable of targeting non-self DNA or RNA for degradation in a sequence- and site-specific manner analogous to RNA interference. Although the complexes display considerable diversity in their composition and architecture, many basic mechanisms underlying target recognition and cleavage are highly conserved...
October 5, 2017: Cell
Karen L Maxwell
The last decade has seen the fields of molecular biology and genetics transformed by the development of CRISPR-based gene editing technologies. These technologies were derived from bacterial defense systems that protect against viral invasion. Elegant studies focused on the evolutionary battle between CRISPR-encoding bacteria and the viruses that infect and kill them revealed the next step in this arms race, the anti-CRISPR proteins. Investigation of these proteins has provided important new insight into how CRISPR-Cas systems work and how bacterial genomes evolve...
October 5, 2017: Molecular Cell
Antonino Montalbano, Matthew C Canver, Neville E Sanjana
The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas nuclease system is a powerful tool for genome editing, and its simple programmability has enabled high-throughput genetic and epigenetic studies. These high-throughput approaches offer investigators a toolkit for functional interrogation of not only protein-coding genes but also noncoding DNA. Historically, noncoding DNA has lacked the detailed characterization that has been applied to protein-coding genes in large part because there has not been a robust set of methodologies for perturbing these regions...
October 5, 2017: Molecular Cell
Ying-Chou Chen, Fahim Farzadfard, Nava Gharaei, William C W Chen, Jicong Cao, Timothy K Lu
The genome-wide perturbation of transcriptional networks with CRISPR-Cas technology has primarily involved systematic and targeted gene modulation. Here, we developed PRISM (Perturbing Regulatory Interactions by Synthetic Modulators), a screening platform that uses randomized CRISPR-Cas transcription factors (crisprTFs) to globally perturb transcriptional networks. By applying PRISM to a yeast model of Parkinson's disease (PD), we identified guide RNAs (gRNAs) that modulate transcriptional networks and protect cells from alpha-synuclein (αSyn) toxicity...
October 5, 2017: Molecular Cell
Karthik Murugan, Kesavan Babu, Ramya Sundaresan, Rakhi Rajan, Dipali G Sashital
CRISPR-Cas systems defend prokaryotes against bacteriophages and mobile genetic elements and serve as the basis for revolutionary tools for genetic engineering. Class 2 CRISPR-Cas systems use single Cas endonucleases paired with guide RNAs to cleave complementary nucleic acid targets, enabling programmable sequence-specific targeting with minimal machinery. Recent discoveries of previously unidentified CRISPR-Cas systems have uncovered a deep reservoir of potential biotechnological tools beyond the well-characterized Type II Cas9 systems...
October 5, 2017: Molecular Cell
Eugene V Koonin, Kira S Makarova
The CRISPR-Cas systems of bacterial and archaeal adaptive immunity show multifaceted evolutionary relationships with at least five classes of mobile genetic elements (MGE). First, the adaptation module of CRISPR-Cas that is responsible for the formation of the immune memory apparently evolved from a Casposon, a self-synthesizing transposon that employs the Cas1 protein as the integrase and might have brought additional cas genes to the emerging immunity loci. Second, a large subset of type III CRISPR-Cas systems recruited a reverse transcriptase from a Group II intron, providing for spacer acquisition from RNA...
September 18, 2017: Genome Biology and Evolution
Emily Roggenkamp, Rachael M Giersch, Emily Wedeman, Muriel Eaton, Emily Turnquist, Madison N Schrock, Linah Alkotami, Thitikan Jirakittisonthon, Samantha E Schluter-Pascua, Gareth H Bayne, Cory Wasko, Megan Halloran, Gregory C Finnigan
Saccharomyces cerevisiae continues to serve as a powerful model system for both basic biological research and industrial application. The development of genome-wide collections of individually manipulated strains (libraries) has allowed for high-throughput genetic screens and an emerging global view of this single-celled Eukaryote. The success of strain construction has relied on the innate ability of budding yeast to accept foreign DNA and perform homologous recombination, allowing for efficient plasmid construction (in vivo) and integration of desired sequences into the genome...
2017: Frontiers in Microbiology
Wenyuan Han, Saifu Pan, Blanca López-Méndez, Guillermo Montoya, Qunxin She
CRISPR-Cas systems protect prokaryotes against invading viruses and plasmids. The system is associated with a large number of Cas accessory proteins among which many contain a CARF (CRISPR-associated Rossmann fold) domain implicated in ligand binding and a HEPN (higher eukaryotes and prokaryotes nucleotide-binding) nuclease domain. Here, such a dual domain protein, i.e. the Sulfolobus islandicus Csx1 (SisCsx1) was characterized. The enzyme exhibited metal-independent single-strand specific ribonuclease activity...
August 16, 2017: Nucleic Acids Research
Yingjun Li, Yan Zhang, Jinzhong Lin, Saifu Pan, Wenyuan Han, Nan Peng, Yun Xiang Liang, Qunxin She
CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated) systems provide adaptive immunity against invasive nucleic acids guided by CRISPR RNAs (crRNAs) in archaea and bacteria. Type III CRISPR-Cas effector complexes show RNA cleavage and RNA-activated DNA cleavage activity, representing the only known system of dual nucleic acid interference. Here, we investigated the function of Cmr1 by genetic assays of DNA and RNA interference activity in the mutants and biochemical characterization of their mutated Cmr complexes...
September 5, 2017: Nucleic Acids Research
Omar O Abudayyeh, Jonathan S Gootenberg, Patrick Essletzbichler, Shuo Han, Julia Joung, Joseph J Belanto, Vanessa Verdine, David B T Cox, Max J Kellner, Aviv Regev, Eric S Lander, Daniel F Voytas, Alice Y Ting, Feng Zhang
RNA has important and diverse roles in biology, but molecular tools to manipulate and measure it are limited. For example, RNA interference can efficiently knockdown RNAs, but it is prone to off-target effects, and visualizing RNAs typically relies on the introduction of exogenous tags. Here we demonstrate that the class 2 type VI RNA-guided RNA-targeting CRISPR-Cas effector Cas13a (previously known as C2c2) can be engineered for mammalian cell RNA knockdown and binding. After initial screening of 15 orthologues, we identified Cas13a from Leptotrichia wadei (LwaCas13a) as the most effective in an interference assay in Escherichia coli...
October 4, 2017: Nature
Iñigo De Miguel Beriain
The development of clustered regularly interspaced short palindromic repeats (CRISPR)-Cas gene-modification technologies has opened impressive possibilities for the biomedical sciences. However, their application to human embryos and early fetuses has raised huge ethical and legal discussions because it affects the human germline. This paper provides a critical and in-depth analysis of the current legal framework on this topic in the EU context and at the national level in the member states. It also offers an alternative interpretation of the regulation, so as to help researchers, practitioners, policy makers and society as a whole to find efficient responses to challenges that cannot wait for a legally updated answer...
September 2017: Regenerative Medicine
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