Arrangement of tRNAs in pre- and posttranslocational ribosomes revealed by electron cryomicroscopy.
The three-dimensional structure of the translating 70S E. coli ribosome is presented in its two main conformations: the pretranslocational and the posttranslocational states. Using electron cryomicroscopy and angular reconstitution, structures at 20 A resolution were obtained, which, when compared with our earlier reconstruction of "empty" ribosomes, showed densities corresponding to tRNA molecules--at the P and E sites for posttranslocational ribosomes and at the A and P sites for pretranslocational ribosomes. The P-site tRNA lies directly above the bridge connecting the two ribosomal subunits, with the A-site tRNA fitted snugly against it at an angle of approximately 50 degrees, toward the L7/L12 side of the ribosome. The E-site tRNA appears to lie between the side lobe of the 30S subunit and the L1 protuberance.
Stark
H
H
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany.
Orlova
E V
EV
Rinke-Appel
J
J
Jünke
N
N
Mueller
F
F
Rodnina
M
M
Wintermeyer
W
W
Brimacombe
R
R
van Heel
M
M
D001665:Binding Sites; D004926:Escherichia coli; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods*; D008958:Models, Molecular; D011132:Polyribosomes / Q000648:ultrastructure; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000648:ultrastructure*; D012270:Ribosomes / Q000648:ultrastructure*
D012343:RNA, Transfer