4X4P: Crystal structure of the A.fulgidus CCA-adding enzyme in complex with a G70A arginyl-tRNA minihelix ending in CCAC

Citation:
Abstract
Transcription in eukaryotes produces a number of long noncoding RNAs (lncRNAs). Two of these, MALAT1 and Menbeta, generate a tRNA-like small RNA in addition to the mature lncRNA. The stability of these tRNA-like small RNAs and bona fide tRNAs is monitored by the CCA-adding enzyme. Whereas CCA is added to stable tRNAs and tRNA-like transcripts, a second CCA repeat is added to certain unstable transcripts to initiate their degradation. Here, we characterize how these two scenarios are distinguished. Following the first CCA addition cycle, nucleotide binding to the active site triggers a clockwise screw motion, producing torque on the RNA. This ejects stable RNAs, whereas unstable RNAs are refolded while bound to the enzyme and subjected to a second CCA catalytic cycle. Intriguingly, with the CCA-adding enzyme acting as a molecular vise, the RNAs proofread themselves through differential responses to its interrogation between stable and unstable substrates.
PDB ID: 4X4PDownload
MMDB ID: 126973
PDB Deposition Date: 2014/12/3
Updated in MMDB: 2017/12
Experimental Method:
x-ray diffraction
Resolution: 3  Å
Source Organism:
Archaeoglobus fulgidus DSM 4304
Similar Structures:
Biological Unit for 4X4P: dimeric; determined by author and by software (PISA)
Molecular Components in 4X4P
Label Count Molecule
Protein (1 molecule)
1
Cca-adding Enzyme(Gene symbol: AF_RS10845)
Molecule annotation
Nucleotide(1 molecule)
1
G70a tRNA Minihelix Ending in Ccac
Molecule annotation
Chemicals (5 molecules)
1
5
* Click molecule labels to explore molecular sequence information.

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