Ribosomal Protein S7 from
Bacillus stearothermophilus and Pyrococcus horikoshii

Ribosomal protein S7 is located at the head of the small subunit facing to the decoding center. It is one of the primary 16S rRNA binding proteins responsible for initiating the assembly of the head of the 30S subunit. It is also the major protein component cross-linked with tRNA molecules bound at both A and P sites.
The structure of ribosomal protein S7 from Bacillus stearothermophilus and Pyrococcus horikoshii has been solved by the multiwavelength anomalous diffraction method using Se-Met substituted proteins. The molecule consists of a helical hydrophobic core domain and a beta-ribbon arm extending from the hydrophobic core. The helical core domain is composed of a pair of entangled helix-turn-helix motifs similar to a DNA architectural factor. Highly conserved basic and aromatic residues are clustered on one face of the S7 molecule and create a 16S rRNA contact surface.
The molecular feature, together with former cross-link experiments, suggests how S7 binds to the 3' major domain of 16S rRNA and mediates the folding of 16S rRNA to create the ribosome decoding center.

References

• The structure of the archaebacterial ribosomal protein S7 and its possible interaction with 16S rRNA
  Harumi Hosaka, Min Yao, Makoto Kimura, and Isao Tanaka
  J. Biochem. in press (2001)

• Matching the crystallographic structure of ribosomal protein S7 to a three-dimensional model of the 16S ribosomal RNA
  Isao Tnaka, Atsushi Nakagawa, Harumi Hosaka, Soichi Wakatsuki, Florian Mueller and Tichard Brimacombe
  RNA 4, 542-550 (1998)

• Ribosomal protein S7: a new RNA-binding motif with structural similarities to a DNA architechtural factor
  Harumi Hosaka, Atsushi Nakagawa, Isao Tanaka, Nao Harada, Kazunari Sano, Makoto Kimura, Min Yao and Soichi Wakatsushi
  Structure, 5, 1199-1208 (1997)

• Crystallization and Preliminary X-Ray Crystallographic Study of the Ribosomal Protein S7 from Bacillux stearothermophilus
  Nao Harada, Kazunari Sano, Makoto Kimura, Harumi Hosaka, Atsushi Nakagawa and Isao Tanaka
  J. Struct. Biol., 120, 112-114 (1997)