9NL3

Structure of R2 retrotransposon protein from Taeniopygia guttata initiating target-primed reverse transcription

Summary for 9NL3

• Entry DOI: 10.2210/pdb9nl3/pdb
• EMDB information: 49516
• Descriptor: R2 retrotransposon protein, Bottom strand for target rDNA, Primer, ... (8 entities in total)
• Functional Keywords: retrotransposon, reverse transcriptase, rna binding protein-rna-dna complex, rna binding protein/rna/dna
• Biological source: Taeniopygia guttata (zebra finch); More
• Total number of polymer chains: 5
• Total formula weight: 277012.05

Authors

Thawani, A.,Collins, K.,Nogales, E. (deposition date: 2025-03-02, release date: 2025-06-18, Last modification date: 2025-07-02)

Primary citation

Thawani, A.,Rodriguez-Vargas, A.,Van Treeck, B.,Hassan, N.T.,Adelson, D.L.,Nogales, E.,Collins, K.
Structures of vertebrate R2 retrotransposon complexes during target-primed reverse transcription and after second-strand nicking.
Sci Adv, 11:eadu5533-eadu5533, 2025

PubMed Abstract: R2 retrotransposons are site-specific eukaryotic non-long terminal repeat retrotransposons that copy and paste into gene loci encoding ribosomal RNAs. Recently, we demonstrated that avian A-clade R2 proteins achieve efficient and precise insertion of transgenes into their native safe-harbor loci in human cells. The features of A-clade R2 proteins that support gene insertion are not well characterized. Here, we report high-resolution cryo-electron microscopy structures of two vertebrate A-clade R2 proteins at the initiation of target-primed reverse transcription and after cDNA synthesis and second-strand nicking. Using biochemical and cellular assays, we illuminate the basis for high selectivity of template use and unique roles for each of the three zinc-finger domains in nucleic acid recognition. Reverse transcriptase active site architecture is reinforced by an unanticipated insertion motif specific to vertebrate A-clade R2 proteins. Our work provides the first insights into A-clade R2 protein structure during gene insertion and may enable future improvement and adaptation of R2-based systems for precise transgene insertion.

PubMed: 40540573
DOI: 10.1126/sciadv.adu5533

Experimental method

ELECTRON MICROSCOPY (3.2 Å)