CRISPR-Cas systems (clustered regularly interspaced short palindromic repeats, CRISPR-associated proteins) enable microbes to acquire immunity against bacteriophages and plasmids, and they also function as transformative tools for genome editing in a wide range of cell types. Fundamental to these systems are RNA-guided nucleases, such as the Cas9 (type II) and Cas12 (type V) families that use CRISPR RNA (crRNA) to recognize foreign double-stranded DNA (dsDNA) by forming an R-loop structure in which 20 nucleotides (nts) of the crRNA (the crRNA “spacer”) base pair with one strand of the target DNA. Although CRISPRs are typically encoded in the genomes of bacteria and archaea, the hypercompact CRISPR-CasΦ system (type V-J, Cas12j) occurs exclusively in bacteriophages. CRISPR-CasΦ genomic loci comprise solely the casΦ effector gene and a short CRISPR sequence array containing 36-base pair sequence repeats flanking an average of five unique spacer sequences. The CasΦ protein, which is distantly related to other type V (Cas12) enzymes based on homology of its Mg2+-dependent RuvC endonuclease domain. Here you have the Cryo-EM structure of the minimalist Cas005-crRNA-DNA complex at 3.1 Angstroms resolution, from Biggievirus Mos11 (PDB code: 8IEW)

#molecularart ... #crispr ..: #virus ... #CasΦ,,, #cryoem

Structure rendered with @proteinimaging, background generated with @stylar.ai_official and depicted with @corelphotopaint