6MEC

Structure of a group II intron retroelement after DNA integration

Summary for 6MEC

• Entry DOI: 10.2210/pdb6mec/pdb
• EMDB information: 9106
• Descriptor: T.el4h RNA, Sense Target DNA, Maturase reverse transcriptase, ... (5 entities in total)
• Functional Keywords: group ii intron, retroelement, retrotransposition, rna-dna-rna binding protein complex, rna/dna/rna binding protein
• Biological source: Thermosynechococcus elongatus; More
• Total number of polymer chains: 3
• Total formula weight: 361214.69

Authors

Haack, D.,Yan, X.,Zhang, C.,Hingey, J.,Lyumkis, D.,Baker, T.S.,Toor, N. (deposition date: 2018-09-06, release date: 2019-08-14, Last modification date: 2024-03-13)

Primary citation

Haack, D.B.,Yan, X.,Zhang, C.,Hingey, J.,Lyumkis, D.,Baker, T.S.,Toor, N.
Cryo-EM Structures of a Group II Intron Reverse Splicing into DNA.
Cell, 178:612-623.e12, 2019

PubMed Abstract: Group II introns are a class of retroelements that invade DNA through a copy-and-paste mechanism known as retrotransposition. Their coordinated activities occur within a complex that includes a maturase protein, which promotes splicing through an unknown mechanism. The mechanism of splice site exchange within the RNA active site during catalysis also remains unclear. We determined two cryo-EM structures at 3.6-Å resolution of a group II intron reverse splicing into DNA. These structures reveal that the branch-site domain VI helix swings 90°, enabling substrate exchange during DNA integration. The maturase assists catalysis through a transient RNA-protein contact with domain VI that positions the branch-site adenosine for lariat formation during forward splicing. These findings provide the first direct evidence of the role the maturase plays during group II intron catalysis. The domain VI dynamics closely parallel spliceosomal branch-site helix movement and provide strong evidence for a retroelement origin of the spliceosome.

PubMed: 31348888
DOI: 10.1016/j.cell.2019.06.035

Experimental method

ELECTRON MICROSCOPY (3.6 Å)