5D1O: Archaeal Atp-dependent Rna Ligase - Form 1

Citation:
Abstract
An ATP-dependent RNA ligase from Methanobacterium thermoautotrophicum (MthRnl) catalyzes intramolecular ligation of single-stranded RNA to form a closed circular RNA via covalent ligase-AMP and RNA-adenylylate intermediate. Here, we report the X-ray crystal structures of an MthRnl*ATP complex as well as the covalent MthRnl-AMP intermediate. We also performed structure-guided mutational analysis to survey the functions of 36 residues in three component steps of the ligation pathway including ligase-adenylylation (step 1), RNA adenylylation (step 2) and phosphodiester bond synthesis (step 3). Kinetic analysis underscored the importance of motif 1a loop structure in promoting phosphodiester bond synthesis. Alanine substitutions of Thr117 or Arg118 favor the reverse step 2 reaction to deadenylate the 5'-AMP from the RNA-adenylate, thereby inhibiting step 3 reaction. Tyr159, Phe281 and Glu285, which are conserved among archaeal ATP-dependent RNA ligases and are situated on the surface of the enzyme, are required for RNA binding. We propose an RNA binding interface of the MthRnl based on the mutational studies and two sulfate ions that co-crystallized at the active site cleft in the MthRnl-AMP complex.
PDB ID: 5D1ODownload
MMDB ID: 137249
PDB Deposition Date: 2015/8/4
Updated in MMDB: 2017/10
Experimental Method:
x-ray diffraction
Resolution: 2.65  Å
Source Organism:
Similar Structures:
Biological Unit for 5D1O: dimeric; determined by author and by software (PISA)
Molecular Components in 5D1O
Label Count Molecule
Proteins (2 molecules)
1
Atp-dependent RNA Ligase
Molecule annotation
1
Atp-dependent RNA Ligase
Molecule annotation
Chemicals (7 molecules)
1
1
2
5
3
1
* Click molecule labels to explore molecular sequence information.

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