2VS1: The Crystal Structure Of Pyrococcus Abyssi Trna (uracil-54, C5)- Methyltransferase In Complex With S-adenosyl-l-homocysteine

Citation:
Abstract
The 5-methyluridine is invariably found at position 54 in the TPsiC loop of tRNAs of most organisms. In Pyrococcus abyssi, its formation is catalyzed by the S-adenosyl-l-methionine-dependent tRNA (uracil-54, C5)-methyltransferase ((Pab)TrmU54), an enzyme that emerged through an ancient horizontal transfer of an RNA (uracil, C5)-methyltransferase-like gene from bacteria to archaea. The crystal structure of (Pab)TrmU54 in complex with S-adenosyl-l-homocysteine at 1.9 A resolution shows the protein organized into three domains like Escherichia coli RumA, which catalyzes the same reaction at position 1939 of 23S rRNA. A positively charged groove at the interface between the three domains probably locates part of the tRNA-binding site of (Pab)TrmU54. We show that a mini-tRNA lacking both the D and anticodon stem-loops is recognized by (Pab)TrmU54. These results were used to model yeast tRNA(Asp) in the (Pab)TrmU54 structure to get further insights into the different RNA specificities of RumA and (Pab)TrmU54. Interestingly, the presence of two flexible loops in the central domain, unique to (Pab)TrmU54, may explain the different substrate selectivities of both enzymes. We also predict that a large TPsiC loop conformational change has to occur for the flipping of the target uridine into the (Pab)TrmU54 active site during catalysis.
PDB ID: 2VS1Download
MMDB ID: 65827
PDB Deposition Date: 2008/4/17
Updated in MMDB: 2008/09
Experimental Method:
x-ray diffraction
Resolution: 2.1  Å
Source Organism:
Similar Structures:
Biological Unit for 2VS1: monomeric; determined by software (PQS)
Molecular Components in 2VS1
Label Count Molecule
Protein (1 molecule)
1
Uncharacterized RNA Methyltransferase Pyrab10780(Gene symbol: PAB_RS05745)
Molecule annotation
Chemicals (2 molecules)
1
1
2
1
* Click molecule labels to explore molecular sequence information.

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