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Cas12a is an RNA‐guided DNA endonuclease of the type V‐A CRISPR‐Cas system that has evolved convergently with the type II Cas9 protein. We previously showed that proline substitutions in the bridge helix (BH) impart target DNA cleavage selectivity inStreptococcus pyogenes(Spy) Cas9. Here, we examined a BH variant of Cas12a fromFrancisella novicida(FnoCas12aKD2P) to test mechanistic conservation. Our results show that for RNA‐guided DNA cleavage (cis‐activity), FnoCas12aKD2Paccumulates nicked products while cleaving supercoiled DNA substrates with mismatches, with certain mismatch positions being more detrimental for linearization. FnoCas12aKD2Palso possess reducedtrans‐single‐stranded DNA cleavage activity. These results implicate the BH in substrate selectivity in bothcis‐andtrans‐cleavages and show its conserved role in target discrimination among Cas nucleases.
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A unique binding mode of P1′ Leu-containing target sequences for Streptococcus pyogenes sortase A results in alternative cleavage
Vogelet al.reveals the stereochemical basis of alternative substrate cleavage byS. pyogenesSrtA for ligands with a P1′ Leu residue. The substrate adopts puckered alternative binding, whereby cleavage occurs between the P1′ and P2′ positions.
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- PAR ID:
- 10496212
- Publisher / Repository:
- RSC Chemical Biology
- Date Published:
- Journal Name:
- RSC Chemical Biology
- Volume:
- 5
- Issue:
- 1
- ISSN:
- 2633-0679
- Page Range / eLocation ID:
- 30 to 40
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d3cb00129f
