Lysosomal endonuclease RNase T2 and PLD exonucleases cooperatively generate RNA ligands for TLR7 activation

Bérouti, Marleen; Lammens, Katja; Heiss, Matthias; Hansbauer, Larissa; Bauernfried, Stefan; Stöckl, Jan; Pinci, Francesca; Piseddu, Ignazio; Greulich, Wilhelm; Wang, Meiyue; Jung, Christophe; Fröhlich, Thomas; Carell, Thomas ; Hopfner, Karl-Peter and Hornung, Veit (2024): Lysosomal endonuclease RNase T2 and PLD exonucleases cooperatively generate RNA ligands for TLR7 activation. In: Immunity, Vol. 57, No. 7: pp. 1482-1496

Abstract

Toll-like receptor 7 (TLR7) is essential for recognition of RNA viruses and initiation of antiviral immunity. TLR7 contains two ligand-binding pockets that recognize different RNA degradation products: pocket 1 recognizes guanosine, while pocket 2 coordinates pyrimidine-rich RNA fragments. We found that the endonuclease RNase T2, along with 5′ exonucleases PLD3 and PLD4, collaboratively generate the ligands for TLR7. Specifically, RNase T2 generated guanosine 2′,3′-cyclic monophosphate-terminated RNA fragments. PLD exonuclease activity further released the terminal 2′,3′-cyclic guanosine monophosphate (2',3'-cGMP) to engage pocket 1 and was also needed to generate RNA fragments for pocket 2. Loss-of-function studies in cell lines and primary cells confirmed the critical requirement for PLD activity. Biochemical and structural studies showed that PLD enzymes form homodimers with two ligand-binding sites important for activity. Previously identified disease-associated PLD mutants failed to form stable dimers. Together, our data provide a mechanistic basis for the detection of RNA fragments by TLR7.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Biochemistry; Chemistry and Pharmacy > Department of Chemistry; Chemistry and Pharmacy > GeneCenter; Medicine > Medical Center of the University of Munich > Medical Clinic and Outpatient Clinic II (Gastroenterology, Hepatology)
• Subjects: 500 Science > 540 Chemistry; 500 Science > 570 Life sciences; biology; 600 Technology > 610 Medicine and health
• ISSN: 10747613
• Language: English