9D5X

Structure of G2L4 RT Apoenzyme

Summary for 9D5X

• Entry DOI: 10.2210/pdb9d5x/pdb
• Related: 9D4S
• Descriptor: Group II intron-like 4 reverse transcriptase, UREA (3 entities in total)
• Functional Keywords: group ii intron reverse transcriptase, microhomology mediated end joining, dna repair, dna binding protein
• Biological source: Gammaproteobacteria
• Total number of polymer chains: 2
• Total formula weight: 92168.11

Authors

Guo, M.,Stamos, J.L.,Zhang, Y. (deposition date: 2024-08-14, release date: 2025-08-06)

Primary citation

Park, S.K.,Guo, M.,Stamos, J.L.,Kim, W.,Lee, S.,Zhang, Y.J.,Lambowitz, A.M.
Structural basis for the evolution of a domesticated group II intron-like reverse transcriptase to function in host cell DNA repair.
Proc.Natl.Acad.Sci.USA, 122:e2504208122-e2504208122, 2025

PubMed Abstract: A previous study found that a bacterial group II intron-like reverse transcriptase (G2L4 RT) evolved to function in double-strand break repair (DSBR) via microhomology-mediated end-joining (MMEJ) and that a mobile group II intron-encoded RT has a basal DSBR activity that uses conserved structural features of non-long terminal repeat (non-LTR)-retroelement RTs. Here, we determined G2L4 RT apoenzyme and snap-back DNA synthesis structures revealing unique structural adaptations that optimized its cellular function in DSBR. These included an RT3a structure that stabilizes the apoenzyme in an inactive conformation until encountering a DNA substrate; a longer N-terminal extension/RT0-loop with conserved residues that together with a modified active site favors strand annealing; and a conserved dimer interface that localizes G2L4 RT homodimers to DSBR sites with both monomers positioned for MMEJ. Our findings reveal how an RT can function in DNA repair and suggest ways of optimizing related RTs for genome engineering applications.

PubMed: 40729381
DOI: 10.1073/pnas.2504208122

Experimental method

X-RAY DIFFRACTION (2.61 Å)