PMID: 23812722 , Related PDB ids: 4KBT, 4KBU, 4KBV, 4KBW, 4KCY, 4KCZ, 4KD0, 4KD2, 4KD8, 4KD9, 4KDA, 4KDB, 4KDG, 4KDH, 4KDJ, 4KDK

Authors:

Zhou J, Lancaster L, Donohue JP, Noller HF

Title:

Crystal structures of EF-G-ribosome complexes trapped in intermediate states of translocation.

Journal:

Science. 2013 Jun 28;340(6140):1236086. doi: 10.1126/science.1236086.

Abstract:

Translocation of messenger and transfer RNA (mRNA and tRNA) through the ribosome is a crucial step in protein synthesis, whose mechanism is not yet understood. The crystal structures of three Thermus ribosome-tRNA-mRNA-EF-G complexes trapped with beta,gamma-imidoguanosine 5'-triphosphate (GDPNP) or fusidic acid reveal conformational changes occurring during intermediate states of translocation, including large-scale rotation of the 30S subunit head and body. In all complexes, the tRNA acceptor ends occupy the 50S subunit E site, while their anticodon stem loops move with the head of the 30S subunit to positions between the P and E sites, forming chimeric intermediate states. Two universally conserved bases of 16S ribosomal RNA that intercalate between bases of the mRNA may act as "pawls" of a translocational ratchet. These findings provide new insights into the molecular mechanism of ribosomal translocation.