Cas1 integrase is the key enzyme of the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas adaptation module that mediates acquisition of spacers derived from foreign DNA by CRISPR arrays. In diverse bacteria, the cas1 gene is fused (or adjacent) to a gene encoding a reverse transcriptase (RT) related to group II intron RTs. An RT-Cas1 fusion protein has been recently shown t...

Bacterial CRISPR-Cas adaptive immune systems use small guide RNAs to protect against phage infection and invasion by foreign genetic elements. We previously demonstrated that a group of Pseudomonas aeruginosa phages encode anti-CRISPR proteins that inactivate the type I-F and I-E CRISPR-Cas systems using distinct mechanisms. Here, we present the three-dimensional structure of an anti-CRISPR pro...

The term genome refers to the total genetic composition of an organism or species. The normal genes transcribe and translate into functional gene products, which in turn bring about a normal phenotype. Genomics, the study of genomes has revealed the significant level of diversity in the human genome attributed not only to single nucleotide polymorphisms (SNPs) but structural variations as well....

The CRISPR (clustered regularly interspaced short palindromic repeat)-Cas9 (CRISPR-associated nuclease 9) system is a versatile tool for genome engineering that uses a guide RNA (gRNA) to target Cas9 to a specific sequence. This simple RNA-guided genome-editing technology has become a revolutionary tool in biology and has many innovative applications in different fields. In this review, we brie...

The recently discovered clustered regularly interspaced short palindromic repeat (CRISPR)-mediated virus defense represents an adaptive immune system in many bacteria and archaea. Small CRISPR RNAs cause cleavage of complementary invading nucleic acids in conjunction with an associated protein or a protein complex. Here, we show CRISPR-mediated cleavage of mRNA from an invading virus in the hyp...

Type I CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas (CRISPR-associated) systems exist in bacterial and archaeal organisms and provide immunity against foreign DNA. The Cas protein content of the DNA interference complexes (termed Cascade) varies between different CRISPR-Cas subtypes. A minimal variant of the Type I-F system was identified in proteobacterial species inc...

Clustered regularly interspaced short palindromic repeats (CRISPRs) are a family of DNA direct repeats found in many prokaryotic genomes. Repeats of 21-37 bp typically show weak dyad symmetry and are separated by regularly sized, nonrepetitive spacer sequences. Four CRISPR-associated (Cas) protein families, designated Cas1 to Cas4, are strictly associated with CRISPR elements and always occur n...

Plant viruses infect many economically important crops, including wheat, cotton, maize, cassava, and other vegetables. These viruses pose a serious threat to agriculture worldwide, as decreases in cropland area per capita may cause production to fall short of that required to feed the increasing world population. Under these circumstances, conventional strategies can fail to control rapidly evo...

CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR associated nuclease 9) systems have emerged as versatile and convenient (epi)genome editing tools and have become an important player in medical genetic research. CRISPR-Cas9 and its variants such as catalytically inactivated Cas9 (dead Cas9, dCas9) and scaffold-incorporating single guide sgRNA (scRNA) have been appli...

CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 gene editing technology is derived from a microbial adaptive immune system, where bacteriophages are often the intended target. Natural inhibitors of CRISPR-Cas9 enable phages to evade immunity and show promise in controlling Cas9-mediated gene editing in human cells. However, the mechanism of CRISPR-Cas9 inhibition is not ...