Targeted DNA transposition in vitro using a dCas9-transposase fusion protein

Bhatt, Shivam; Chalmers, Ronald

Abstract

Homology-directed genome engineering is limited by transgene size. Although DNA transposons are more efficient with large transgenes, random integrations are potentially mutagenic. Here we present an in vitro mechanistic study that demonstrates efficient Cas9 targeting of the mariner transposon Hsmar1. Integrations were unidirectional and tightly constrained to one side of the sgRNA binding site. Further analysis of the nucleoprotein intermediates demonstrated that the transposase and Cas9 moieties can bind their respective substrates independently or in concert. Kinetic analysis of the reaction in the presence of the Cas9 target–DNA revealed a delay between first and second strand cleavage at the transposon end. This step involves a significant conformational change that may be hindered by the properties of the interdomainal linker. Otherwise, the transposase moiety behaved normally and was proficient for integration in vitro and in Escherichia coli. Specific integration into the lacZ gene in E. coli was obscured by a high background of random integrations. Nevertheless, Cas9 is an attractive candidate for transposon-targeting because it has a high affinity and long dwell-time at its target site. This will facilitate a future optogenetic strategy for the temporal control of integration, which will increase the ratio of targeted to untargeted events.

Citation

Bhatt, S., & Chalmers, R. (2019). Targeted DNA transposition in vitro using a dCas9-transposase fusion protein. Nucleic Acids Research, 47(15), 8126–8135. https://doi.org/10.1093/nar/gkz552

• Journal Article Type: Article
• Acceptance Date: Jun 11, 2019
• Online Publication Date: Jun 25, 2019
• Publication Date: Sep 5, 2019
• Deposit Date: Oct 11, 2019
• Publicly Available Date: Oct 11, 2019
• Journal: Nucleic Acids Research
• Print ISSN: 0305-1048
• Electronic ISSN: 1362-4962
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 47
• Issue: 15
• Pages: 8126–8135
• DOI: https://doi.org/10.1093/nar/gkz552
• Keywords: Genetics
• Public URL: https://nottingham-repository.worktribe.com/output/2466823
• Publisher URL: https://academic.oup.com/nar/article/47/15/8126/5523009