TIGR-Tas RNA-Guided DNA-Targeting Systems

Faure, Saito, Wilkinson, Quinones-Olvera, Xu, Flam-Shepherd, Kim, Reddy, Zhu, Evgeniou, Koonin, Macrae & Zhang, "TIGR-Tas: A family of modular RNA-guided DNA-targeting systems in prokaryotes and their viruses" (Science, published online 2025-02-27, DOI 10.1126/science.adv9789) -- discovered via iterative structural and sequence homology-based computational mining starting from Cas9's own guide-RNA-interaction domain (see the linked precursor node), not from a CRISPR locus. Found in phage and other mobile genetic elements. Unlike CRISPR-Cas, TIGR systems have no PAM (protospacer-adjacent motif) targeting restriction and are substantially more compact, framed by the authors and subsequent commentary as a potential therapeutic-delivery advantage. Discovered in Feng Zhang's lab at the Broad Institute/MIT. Presented in the literature as a genuinely new, non-CRISPR RNA-guided system, not a Cas9 variant. Very early: 51 citations as of 2026-09-03, no independent replication or applied translation documented yet -- status set to emerging, not foundational, on that basis.