Rk. Agrawal et al., Localization of L11 protein on the ribosome and elucidation of its involvement in EF-G-dependent translocation, J MOL BIOL, 311(4), 2001, pp. 777-787
L11 protein is located at the base of the L7/LI2 stalk of the 50 S subunit
of the Escherichia coli ribosome. Because of the flexible nature of the reg
ion, recent X-ray crystallographic studies of the 50 S subunit failed to lo
cate the N-terminal domain of the protein. We have determined the position
of the complete L11 protein by comparing a three-dimensional cryo-EM recons
truction of the 70 S ribosome, isolated from a mutant lacking ribosomal pro
tein L11, with the three-dimensional map of the wild-type ribosome. Fitting
of the X-ray coordinates of L11-23 S RNA complex and EF-G into the cryo-EM
maps combined with molecular modeling, reveals that, following EF-G-depend
ent GTP hydrolysis, domain V of EF-G intrudes into the cleft between the 23
S ribosomal RNA and the N-terminal domain of L11 (where the antibiotic thi
ostrepton binds), causing the N-terminal domain to move and thereby inducin
g the formation of the arc-like connection with the G' domain of EF-G. The
results provide a new insight into the mechanism of EF-G-depenclent translo
cation.