Programmable remodeling of the can reversibly switch Cas12a activity for more controllable diagnostics.
Evidence
This platform engineering study tested tunable DNA blockers, strand-displacement reactivation, SNV discrimination, one-pot isothermal assays, and detection of Klebsiella pneumoniae and Mycobacterium tuberculosis.
Caveat
The work demonstrates analytical assay control, but it does not establish performance in clinical diagnostic workflows or patient samples.
Simplified
CRISPR-Cas12a has transformative potential in molecular diagnostics owing to its robust signal amplification, but its sustained activity state severely limits temporal programmability and precise nuclease control in complex detection workflows. Here, we demonstrate that the conserved secondary structure itself can be repurposed as a reversible and programmable conformational switch to regulate Cas12a activity. By introducing short complementary DNA blockers of tunable length, we achieved length-dependent disruption and remodeling of scaffold secondary structure, shifting LbCas12a into an inactive conformation. Scaffold structure was subsequently reinstated through either single or cooperative strand displacement activation, enabling time-resolved and on-demand restoration of Cas12a activity. The conserved scaffold ensures intrinsic assay universality, while its programmable rewiring markedly improves discrimination and enables compatibility with one-pot isothermal amplification assays, delivering analytical sensitivity comparable to conventional two-step assays. This regulatory framework was further demonstrated in the detection of Klebsiella pneumoniae and Mycobacterium tuberculosis. By validating the crRNA scaffold as a practical and programmable switch for Cas12a activity control, this work establishes a universal and reversible framework for scaffold rewiring to modulate CRISPR nucleases and offers mechanistic insight to guide future assay engineering.
Key numbers
6.34%
Decrease in Cas12a Activity
Activity dropped to 6.34% relative to the unblocked control after full occlusion.
1.89 to 16.23
Discrimination Factor for
CSDA yielded discrimination factors spanning from 1.89 to 16.23 for .
100%
Activity Recovery Rate
Strand displacement reactions restored Cas12a activity to 100% under optimal conditions.
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