3FUU: T. thermophilus 16S rRNA A1518 and A1519 methyltransferase (KsgA) in complex with Adenosine in space group P212121

Posttranscriptional modification of ribosomal RNA (rRNA) occurs in all kingdoms of life. The S-adenosyl-L-methionine-dependent methyltransferase KsgA introduces the most highly conserved rRNA modification, the dimethylation of A1518 and A1519 of 16S rRNA. Loss of this dimethylation confers resistance to the antibiotic kasugamycin. Here, we report biochemical studies and high-resolution crystal structures of KsgA from Thermus thermophilus. Methylation of 30S ribosomal subunits by T. thermophilus KsgA is more efficient at low concentrations of magnesium ions, suggesting that partially unfolded RNA is the preferred substrate. The overall structure is similar to that of other methyltransferases but contains an additional alpha-helix in a novel N-terminal extension. Comparison of the apoenzyme with complex structures with 5'-methylthioadenosine or adenosine bound in the cofactor-binding site reveals novel features when compared with related enzymes. Several mobile loop regions that restrict access to the cofactor-binding site are observed. In addition, the orientation of residues in the substrate-binding site indicates that conformational changes are required for binding two adjacent residues of the substrate rRNA.
PDB ID: 3FUUDownload
MMDB ID: 70558
PDB Deposition Date: 2009/1/14
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.53  Å
Source Organism:
Similar Structures:
Biological Unit for 3FUU: monomeric; determined by author and by software (PISA)
Molecular Components in 3FUU
Label Count Molecule
Protein (1 molecule)
Dimethyladenosine Transferase(Gene symbol: ksgA)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB