CRISPR-Cas9: Difference between revisions

<scene name='74/742625/Cv/36'>Each 5-bp segment of the hybrid is situated between the palm of one Cas7 subunit (e.g. Cas7.2) and the fingers of the adjacent subunit (e.g. Cas7.3)</scene>. 5-bp segment is colored red. Extensive contacts between the guide region of the crRNA and the Cas7 filament bury a large portion of the crRNA backbone, leaving the bases solvent-exposed. The absence of direct contacts between protein side chains and bases of the crRNA explains the lack of sequence specificity by Cascade for the guide sequence. <scene name='74/742625/Cv/37'>Close-up view of the bound crRNA</scene>. The DNA target has been removed for clarity. Intercalation by Met166 from Cas7 is highlighted. <scene name='74/742625/Cv/38'>Several highly conserved polar and positively charged residues (Arg20, Lys27, Ser40, Gln42, Lys45, and Lys49 - colored in magenta) from the palm of one Cas7 (e.g. Cas7.3) contact the RNA backbone</scene>, while the <scene name='74/742625/Cv/39'>fingers from the adjacent Cas7 (e.g. Cas7.5) subunit (residues 109-111, 163-169, colored in plum) contact both strands of the hybrid across the minor groove</scene>. Of note, the <scene name='74/742625/Cv/40'>Thumb (colored in olive) of one Cas7 subunit (e.g. Cas7.4) pushes through the guide-target hybrid at the 1-bp gaps</scene>. <scene name='74/742625/Cv/32'>Representation of 5 thumbs protruding guide-target hybrid at the 1-bp gaps</scene>. Each displaced RNA nucleotide adopts the syn conformation, is similarly positioned above the backbone of the downstream RNA, and is contacted by <scene name='74/742625/Cv/33'>residues from both the Cas7 palm (e.g. Cas7.4 palm; Ser43 and Arg46) and thumb (e.g. Cas7.3 thumb; Thr201 and Val203)</scene>. Overview of the <scene name='74/742625/Cv1/2'>interactions between the ssDNA target and Cse2.1, Cse2.2, and Cse1</scene>. The proteins are represented as rockets, the DNA as a surface. The positions of the disrupted DNA nucleotides (royal blue) are indicated.