User:Luis Andres Casavilca Ramirez/Sandbox 1

PduCas13b is a class 2 type 4 from Prevotella buccae. As a member of this protein family, it uses a single effector complexed with a CRISPR-RNA to bind and cleave RNA with its twin HEPN domains, activating a general non-specific RNase activity that degrades any nearby transcripts.(1)⁠ However, PduCas13b is structurally and mechanically different from the other Cas13s, as it has a unique linear organization and different dynamics in target recognition.(2)⁠.

Structure

Though the overall conserved bilobed shape of many Class 2 effectors consisting of a recognition and nuclease lobe is present,(2,3)⁠ Cas13b has a unique domain organization even among Cas13s. (Fig.1). A crystal structure of PbuCas13b complexed with a 36-nt direct repeat sequence and a 5-nt spacer at 1.65 Å provides information of the domains’ three dimensional arrange. There are five domains within the effector structure: two HEPN domains (HEPN1 and HEPN2), two mainly helical domains (Helical-1 and Helical-2), and a Lid domain. In addition, crRNA also has a unique structure, since its direct repeat is at the 3’ end and not at the 5’ end as in the other Cas13s (Fig.1).

cnRNA and Targeting

Application