The crystal structure of protein L9 from the Bacillus stearothermophilus ribosome has been determined at 2.8 A resolution using X-ray diffraction methods. This primary RNA-binding protein has a highly elongated and unusual structure consisting of two separated domains joined by a long exposed alpha-helix. Conserved, positively charged and aromatic amino acids on the surfaces of both domains probably represent the sites of specific interactions with 23S rRNA. Comparisons with other prokaryotic L9 sequences show that while the length of the connecting alpha-helix is invariant, the sequence within the exposed central region is not conserved. This suggests that the alpha-helix has an architectural role and serves to fix the relative separation and orientation of the N- and C-terminal domains within the ribosome. The N-terminal domain has structural homology to the smaller ribosomal proteins L7/L12 and L30, and the eukaryotic RNA recognition motif (RRM).
PDB ID: 1DIVDownload
MMDB ID: 55924
PDB Deposition Date: 1996/7/2
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.6  Å
Source Organism:
Similar Structures:
Biological Unit for 1DIV: dimeric; determined by author
Molecular Components in 1DIV
Label Count Molecule
Proteins (2 molecules)
Ribosomal Protein L9
Molecule annotation
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Citing MMDB