The discovery of an adaptive prokaryotic immune system called Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), in which the repeats associate with Cas (CRISPR-associated) proteins, has constituted a revolution in life sciences. CRISPR-Cas systems are highly diverse ribonucleoprotein (RNP) complexes with different evolutionary origins. They are divided into two classes, Class 1 and Class 2, the former including a multi-subunit effector complex and the later a single protein effector. Recently, several CRISPR-Cas machineries have been found associated with Tn7-like transposon systems in types I, IV and V. These CAST systems are a product of an evolutionary process by which Tn7-like transposons recruited the CRISPR-Cas system for transposon mobilization. These complexes do not degrade their target DNA and operate exclusively in prokaryotes. They insert large DNA cargos (10–30 kb) at specific genome regions without the need for homology-directed repair. Therefore, CASTs are thought to provide a very promising system for the development of next-generation gene-editing tools. Here you can see the 2.4 Å cryo-EM structure of the Scytonema hofmannii (sh) TnsB transposase from Type V-K CAST, bound to the strand transfer DNA (PDB code: 8AA5)
#molecularart ... #immolecular ... #crispr ... #transposase ... #genomeediting ... #dnacomplex ... #transfer ... #complex
Structure rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #crispr ... #transposase ... #genomeediting ... #dnacomplex ... #transfer ... #complex
Structure rendered with @proteinimaging and depicted with @corelphotopaint
