Year: 2026
Type: preprint
Abstract: Bacterial small-molecule messengers that function in diverse immune signaling pathways have been thought to derive strictly from biosynthesis using nucleotide and cofactor substrates. Here we report a nuclease-driven immune signaling pathway in which tRNA cleavage generates a specific small molecule that triggers cell death in response to RNA-guided transcript recognition in prokaryotes. We identify a class of type VI-B CRISPR systems in which the RNA-guided nuclease Cas13 and its accessory transmembrane protein, 2TMβ, are co-encoded in an operon and are jointly required for bacteriophage defense. Upon target RNA recognition, Cas13 activates 2TMβ by producing mono- and dinucleotide messengers bearing 2',3'-cyclic uridine phosphate ends by tRNA cleavage. Activated 2TMβ destroys infected cells by forming a multimeric complex that disrupts cell membranes to mediate cell death. These findings demonstrate RNA-programmed tRNA cleavage for second-messenger biogenesis, revealing a new logic for prokaryotic immune signaling.
Authors: Luis E. Valentin-Alvarado, Peter H. Yoon, Santiago C. Lopez, Yekaterina Shulgina, Conner Langeberg, Emily Armbruster, Muhammad Moez Ur-Rehman, Kenneth Loi, Cyntia Taveneau, Isabel Esain-Garcia, Mert Koka, Zeyuan Terry Zhang, Dmitry Kashin, Frank Schwede, Gaetan Burgio, Mitchell R. O’Connell, Erin E. Doherty, Jamie H. D. Cate, Gavin J. Knott, Jennifer A. Doudna
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Awards: G3948510816, NSF Center for Genetically Encoded Materials, G4554029424, Collaborative Research: TRTech-PGR TRACK: Discovery and characterization of small CRISPR systems for virus-based delivery of heritable editing in plants., G8891595196, Molecular mechanisms of RNA-targeting CRISPR-Cas systems and their membrane-associated accessory proteins
OpenAlex ID: W7221067405