The reconstituted and engineered Type I-F CAST is established as a functional platform for programmable DNA insertion in plants and provides a foundation for developing targeted genome-engineering technologies for crop biotechnology.
Abstract
Programmable DNA integration is a major challenge in plant genome engineering. CRISPR-associated transposases (CAST) catalyze efficient RNA-guided DNA integration without double-strand breaks, yet their activity has not been established in plants. Here, we reconstituted and engineered a Type I-F CAST for programmable DNA integration in plant cells. We validated expression of the wild-type Pseudoalteromonas CAST (PseCAST) machinery in plants and established targeted episomal integration in Arabidopsis thaliana protoplasts and chromosomal integration at a transgenic locus in Nicotiana benthamiana. The evolved PseCAST system, evoCAST, showed chromosomal integration efficiencies of 2.7%, representing a 6-fold improvement over wild-type PseCAST. evoCAST also enabled the insertion of cis-regulatory elements into a synthetic landing pad with 8% efficiency. evoCAST was subsequently retargeted to six endogenous genomic loci, demonstrating programmable integration across diverse chromosomal contexts. Finally, a cofactor screen identified the chromatin-associated factor AtHMGB2 as an enhancer of evoCAST-mediated integration activity in plants. These results establish CAST as a functional platform for programmable DNA insertion in plants and provide a foundation for developing targeted genome-engineering technologies for crop biotechnology.
An RNA-guided bridge recombinase system is engineered through rational mutagenesis and AI-assisted directed evolution, enabling programmable chromosomal rearrangements in both plant and mammalian cells and achieving up to a 29.8-fold increase in activity.
Rui Gao, Jingjing Wei, Chao Sun et al.· Trends in Biotechnology· 0 citations
This chapter outlines a comprehensive methodology for the design, assembly, and functional assessment of CRISPR/dCas9 systems optimized for tomato to investigate pathogen-associated responses.
Ananya Mukherjee, Shrabani Basak, Raghuvir Singh et al.· Methods in molecular biology· 0 citations
An improved tool called pSPIN-GG and supporting protocols for simplified CAST-based genome engineering are presented and refinements support accelerated library construction, reduce assembly and screening burden, and expand the accessibility of CAST systems for multiplexed bacterial genome engineering.
Thea C T Irvine, Andrew M Bailey, Thomas E. Gorochowski· Methods in molecular biology· 0 citations
Transposons are fundamental genetic elements that have profoundly shaped the architecture of eukaryotic genomes. Yeasts and filamentous fungi have emerged as important chassis organisms for bioingredient production in synthetic biology and metabolic engineering. In this review, we summarise the current understanding and future opportunities in the development of transposon-based tools for genome engineering in these fungal systems. Fungal inverted terminal repeat (ITR) DNA transposons, as well as long terminal repeat (LTR) and non-LTR retrotransposons, can accelerate genomic mutagenesis, facilitating the screening of superior genotypes and phenotypes. CRISPR-associated transposons (CASTs) hold considerable potential for site-specific integration of large transgenes, bypassing the limitations imposed by low homologous recombination (HR) efficiency in non-Saccharomyces hosts. Overall, transposon-based tools represent a valuable and underexplored avenue to accelerate genome engineering and strain development in yeasts and filamentous fungi.
Bingyin Peng, Masahiro Tominaga, Chengqiang Wang et al.· Yeast· 1 citation
Tandem Interspaced Guide RNA (TIGR)–TIGR-associated (Tas) systems are a newly discovered family of ultracompact, modular RNA-guided DNA-targeting proteins that function without a protospacer adjacent motif (PAM) requirement. Their utility as genome engineering tools in microbes remains unexplored. Here, we report the first functional implementation of TIGR-Tas in Saccharomyces cerevisiae for genome engineering. We show that TasR from Parcubacteria (ParTasR) can be programmed by user-defined tigRNAs to generate targeted DNA double-strand breaks at yeast endogenous loci. By co-delivering ParTasR with customized tigRNAs and donor templates, we achieved precise gene fragment deletion and targeted codon substitutions at multiple genomic loci. The multiplex genome engineering capability of this TIGR-Tas system was demonstrated through high-efficiency multiplex gene disruption and chromosomal assembly of a lycopene biosynthesis pathway while inactivating an endogenous gene. This work establishes TIGR-Tas as a valuable addition to the yeast genome engineering toolbox, particularly for applications requiring PAM-independent targeting or compact delivery.
