Anti-CRISPR (Anti-Clustered Regularly Interspaced Short Palindromic Repeats or Acr) 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. Before the discovery of this type of family proteins, the acquisition of mutations was the only way known that phages could use to avoid CRISPR-Cas mediated shattering, by reducing the binding affinity of the phage and CRISPR. Nonetheless, bacteria have mechanisms to retarget the mutant bacteriophage, a process that it is called "priming adaptation". So, as far as researchers currently know, anti-CRISPR is the most effective way to ensure the survival of phages throughout the infection process of bacteria. The adaptive immune system in Pseudomonas aeruginosa (type I-F) relies on a 350 kDa CRISPR RNA (crRNA)-guided surveillance complex (Csy complex) to bind foreign DNA and recruit a trans-acting nuclease for target degradation. Here, you can see the cryo-electron microscopy (cryo-EM) structure of the Csy complex bound to two different Anti-CRISPR proteins, AcrF1 and AcrF2 (represented as yellow surfaces), at an average resolution of 3.4 Å (PDB code: 5UZ9)
#molecularart ... #immolecular ... #crispr ... #anti-crispr ... #pseudomonas ... #acf ... #DNA ... #immunity ... #bacteria ... #cryoem
Pseudomonas crRNA surveillance complex rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #crispr ... #anti-crispr ... #pseudomonas ... #acf ... #DNA ... #immunity ... #bacteria ... #cryoem
Pseudomonas crRNA surveillance complex rendered with @proteinimaging and depicted with @corelphotopaint
