Emily P. Bentley

Emily P. Bentley is a Blog Writer at Addgene. She earned her PhD in molecular biology and biophysics from Scripps Research, and she loves supporting open science and learning about new research.

Blog articles by Emily P. Bentley

A cartoon of a prime editor with two different edit sequences. The DNA sequences are shown with one strand edited and a 5′ DNA flap, before heteroduplex resolution and DNA repair.  The first edit has an unchanged PAM. This DNA is shown connected to the prime editor by a two-way arrow, indicating that the editor can re-bind. Re-nicking is represented by scissors and would remove the newly edited DNA.  The second edit has an altered PAM. A one-way arrow leads from the prime editor to this edit, indicating that the changed PAM prevents the editor from re-binding.
A decorative image depicting the protein structure of Top7 with a cartoon happy face wearing a Nobel Prize on a ribbon.
Overview of the parts of CRISPR. The bacterial chromosome encodes a tracrRNA (in some systems including Cas9), Cas proteins, and a CRISPR array. The CRISPR array is composed of identical repeat sequences and variable spacer sequences. The array is transcribed and processed into crRNAs, each including one repeat and one spacer. In bacteria, these crRNAs are bound by Cas proteins (Cas9 shown here). The repeat sequence base pairs with the tracrRNA, and the spacer sequence is used to target complementary DNA sequences. In laboratory settings, an sgRNA includes the crRNA and tracrRNA sequences in a “single-guide RNA” that performs both functions. Cas9 cuts both the target and nontarget DNA strands upstream of the PAM site found in the nontarget strand.
Cartoon summary of Cas9 activity.

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