CRISPR is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea. These sequences are derived from DNA fragments of bacteriophages that had previously infected the prokaryote. They are used to detect and destroy DNA from similar bacteriophages during subsequent infections. Hence these sequences play a key role in the antiviral defense system of prokaryotes and provide a form of acquired immunity. CRISPR is found in approximately 50% of sequenced bacterial genomes and nearly 90% of sequenced archaea.
An isopeptide bond is a type of amide bond formed between a carboxyl group of one amino acid and an amino group of another. An isopeptide bond is the linkage between the side chain amino or carboxyl group of one amino acid to the α-carboxyl, α-amino group, or the side chain of another amino acid. In a typical peptide bond, also known as eupeptide bond, the amide bond always forms between the α-carboxyl group of one amino acid and the α-amino group of the second amino acid. Isopeptide bonds are rarer than regular peptide bonds. Isopeptide bonds lead to branching in the primary sequence of a protein. Proteins formed from normal peptide bonds typically have a linear primary sequence.
Robert Bernard Darnell is an American neurooncologist and neuroscientist, founding director and former CEO of the New York Genome Center, the Robert and Harriet Heilbrunn Professor of Cancer Biology at The Rockefeller University, and an Investigator of the Howard Hughes Medical Institute. His research into rare autoimmune brain diseases led to the invention of the HITS-CLIP method to study RNA regulation, and he is developing ways to explore the regulatory portions—known as the "dark matter"—of the human genome.
Sortase refers to a group of prokaryotic enzymes that modify surface proteins by recognizing and cleaving a carboxyl-terminal sorting signal. For most substrates of sortase enzymes, the recognition signal consists of the motif LPXTG (Leu-Pro-any-Thr-Gly), then a highly hydrophobic transmembrane sequence, followed by a cluster of basic residues such as arginine. Cleavage occurs between the Thr and Gly, with transient attachment through the Thr residue to the active site Cys residue, followed by transpeptidation that attaches the protein covalently to cell wall components. Sortases occur in almost all Gram-positive bacteria and the occasional Gram-negative bacterium or Archaea, where cell wall LPXTG-mediated decoration has not been reported. Although sortase A, the "housekeeping" sortase, typically acts on many protein targets, other forms of sortase recognize variant forms of the cleavage motif, or catalyze the assembly of pilins into pili.
In molecular biology, trans-activating crispr RNA (tracrRNA) is a small trans-encoded RNA. It was first discovered by Emmanuelle Charpentier in her study of human pathogen Streptococcus pyogenes, a type of bacteria that causes harm to humanity. In bacteria and archaea; CRISPR-Cas constitute an RNA-mediated defense system which protects against viruses and plasmids. This defensive pathway has three steps. First a copy of the invading nucleic acid is integrated into the CRISPR locus. Next, CRISPR RNAs (crRNAs) are transcribed from this CRISPR locus. The crRNAs are then incorporated into effector complexes, where the crRNA guides the complex to the invading nucleic acid and the Cas proteins degrade this nucleic acid. There are several CRISPR system subtypes.
Jennifer Anne Doudna is an American biochemist who has done pioneering work in CRISPR gene editing, and made other fundamental contributions in biochemistry and genetics. Doudna was one of the first women to share a Nobel in the sciences. She received the 2020 Nobel Prize in Chemistry, with Emmanuelle Charpentier, "for the development of a method for genome editing." She is the Li Ka Shing Chancellor's Chair Professor in the department of chemistry and the department of molecular and cell biology at the University of California, Berkeley. She has been an investigator with the Howard Hughes Medical Institute since 1997.
Cas9 is a 160 kilodalton protein which plays a vital role in the immunological defense of certain bacteria against DNA viruses and plasmids, and is heavily utilized in genetic engineering applications. Its main function is to cut DNA and thereby alter a cell's genome. The CRISPR-Cas9 genome editing technique was a significant contributor to the Nobel Prize in Chemistry in 2020 being awarded to Emmanuelle Charpentier and Jennifer Doudna.
Sortases are membrane anchored enzyme that sort these surface proteins onto the bacterial cell surface and anchor them to the peptidoglycan. There are different types of sortases and each catalyse the anchoring of different proteins to cell walls.
Feng Zhang is a Chinese-American biochemist. Zhang currently holds the James and Patricia Poitras Professorship in Neuroscience at the McGovern Institute for Brain Research and in the departments of Brain and Cognitive Sciences and Biological Engineering at the Massachusetts Institute of Technology. He also has appointments with the Broad Institute of MIT and Harvard. He is most well known for his central role in the development of optogenetics and CRISPR technologies.
CRISPR interference (CRISPRi) is a genetic perturbation technique that allows for sequence-specific repression of gene expression in prokaryotic and eukaryotic cells. It was first developed by Stanley Qi and colleagues in the laboratories of Wendell Lim, Adam Arkin, Jonathan Weissman, and Jennifer Doudna. Sequence-specific activation of gene expression refers to CRISPR activation (CRISPRa).
A protospacer adjacent motif (PAM) is a 2–6-base pair DNA sequence immediately following the DNA sequence targeted by the Cas9 nuclease in the CRISPR bacterial adaptive immune system. The PAM is a component of the invading virus or plasmid, but is not found in the bacterial host genome and hence is not a component of the bacterial CRISPR locus. Cas9 will not successfully bind to or cleave the target DNA sequence if it is not followed by the PAM sequence. PAM is an essential targeting component which distinguishes bacterial self from non-self DNA, thereby preventing the CRISPR locus from being targeted and destroyed by the CRISPR-associated nuclease.
Emmanuelle Marie Charpentier is a French professor and researcher in microbiology, genetics, and biochemistry. As of 2015, she has been a director at the Max Planck Institute for Infection Biology in Berlin. In 2018, she founded an independent research institute, the Max Planck Unit for the Science of Pathogens. In 2020, Charpentier and American biochemist Jennifer Doudna of the University of California, Berkeley, were awarded the Nobel Prize in Chemistry "for the development of a method for genome editing". This was the first science Nobel Prize ever won by two women only.
CRISPR gene editing is a genetic engineering technique in molecular biology by which the genomes of living organisms may be modified. It is based on a simplified version of the bacterial CRISPR-Cas9 antiviral defense system. By delivering the Cas9 nuclease complexed with a synthetic guide RNA (gRNA) into a cell, the cell's genome can be cut at a desired location, allowing existing genes to be removed and/or new ones added in vivo.
Locus Biosciences is a clinical-stage pharmaceutical company, founded in 2015 and based in Research Triangle Park, North Carolina. Locus develops phage therapies based on CRISPR–Cas3 gene editing technology, as opposed to the more commonly used CRISPR-Cas9, delivered by engineered bacteriophages. The intended therapeutic targets are antibiotic-resistant bacterial infections.
Anti-CRISPR is a group of proteins found in phages, that inhibit the normal activity of CRISPR-Cas, the immune system of certain bacteria. CRISPR consists of genomic sequences that can be found in prokaryotic organisms, that come from bacteriophages that infected the bacteria beforehand, and are used to defend the cell from further viral attacks. Anti-CRISPR results from an evolutionary process occurred in phages in order to avoid having their genomes destroyed by the prokaryotic cells that they will infect.
Olaf Schneewind was a German-born American microbiologist who made important contributions to the study of bacterial cell wall composition and assembly as well as the pathogenesis of the microbial species S. aureus. He was elected to the National Academy of Sciences in 2018.
Cas3 is an ATP-dependent single-strand DNA (ssDNA) translocase/helicase enzyme that degrades DNA as part of CRISPR based immunity.
Seth Shipman is an American scientist. Shipman is an assistant professor at the Gladstone Institutes and the University of California, San Francisco, where he researches synthetic biology, genetics, and neuroscience.
Vincent A. Fischetti is a world renowned American microbiologist and immunologist. He is Professor of and Head of the Laboratory of Bacterial Pathogenesis and Immunology at Rockefeller University in New York City. His Laboratory is the oldest continuous laboratory at Rockefeller that started in 1926 and headed by 4 leading scientists over its near 100 year history: Homer Swift, Maclyn McCarty, Emil Gotschlich and now Vincent Fischetti. Keeping with the historical theme of infectious diseases, Fischetti's primary areas of research are bacterial pathogenesis, bacterial genomics, immunology, virology, microbiology, and therapeutics. He was the first scientist to clone and sequence a surface protein on gram-positive bacteria, the M protein from S. pyogenes, and determine its unique coiled-coil structure. He also was the first use phage lysins as a therapeutic and an effective alternative to conventional antibiotics.
CRISPR RNA or crRNA is a RNA transcript from the CRISPR locus. CRISPR-Cas is an adaptive immune system found in bacteria and archaea to protect against mobile genetic elements, like viruses, plasmids, and transposons. The CRISPR locus contains a series of repeats interspaced with unique spacers. These unique spacers can be acquired from MGEs.
