Unveiling Cas8 dynamics and regulation within a transposon-encoded Cascade–TniQ complex

• DOI: 10.1073/pnas.2422895122
• Publication Date: 2025-04-02T15:50:21Z
• Authors: Amun C. Patel; Souvik Sinha; Pablo R. Arantes; Giulia Palermo
• Keywords: Conformational change

The Vibrio cholerae Cascade–TniQ complex unveiled a new paradigm in biology, demonstrating that CRISPR-associated proteins can direct DNA transposition. Despite the tremendous potential of “knocking-in” genes at desired sites, mechanisms underlying binding and transposition remain elusive. In this system, conformational change Cas8 protein is essential for binding, yet how it occurs unclear. Here, structural modeling free energy simulations reconstruct helical bundle reveal an open–closed key complex’s function. We show when binds RNA, changes conformation mediated by interaction with Cas7.1 protein. This promotes bundle’s transition toward open state, priming binding. As target guide opening becomes more favorable, exposing positively charged residues facilitating their DNA, which ultimately leads DNA-binding process to completion. These outcomes provide dynamic representation critical one largest CRISPR systems illustrate its role steps biophysical function, advancing our understanding nucleic acid mechanisms.