4urd | pdb_00004urd
Cryo-EM map of Trigger Factor bound to a translating ribosome
Structural highlights
FunctionTIG_ECOLI Involved in protein export. Acts as a chaperone by maintaining the newly synthesized secretory and non-secretory proteins in an open conformation. Binds to nascent polypeptide chains via ribosomal protein L23 (PubMed:12226666). Functions as a peptidyl-prolyl cis-trans isomerase in vitro, this activity is dispensible in vivo for chaperone activity.[1] [2] [3] Publication Abstract from PubMedTrigger factor (TF) is the only ribosome-associated chaperone in bacteria. It interacts with hydrophobic segments in nascent chain (NCs) as they emerge from the ribosome. TF binds via its N-terminal ribosome-binding domain (RBD) mainly to ribosomal protein uL23 at the tunnel exit on the large ribosomal subunit. Whereas earlier structural data suggested that TF binds as a rigid molecule to the ribosome, recent comparisons of structural data on substrate-bound, ribosome-bound, and TF in solution from different species suggest that this chaperone is a rather flexible molecule. Here, we present two cryo-electron microscopy structures of TF bound to ribosomes translating an mRNA coding for a known TF substrate from Escherichia coli of a different length. The structures reveal distinct degrees of flexibility for the different TF domains, a conformational rearrangement of the RBD upon ribosome binding, and an increase in rigidity within TF when the NC is extended. Molecular dynamics simulations agree with these data and offer a molecular basis for these observations. Dynamic Behavior of Trigger Factor on the Ribosome.,Deeng J, Chan KY, van der Sluis EO, Berninghausen O, Han W, Gumbart J, Schulten K, Beatrix B, Beckmann R J Mol Biol. 2016 Jun 16. pii: S0022-2836(16)30215-7. doi:, 10.1016/j.jmb.2016.06.007. PMID:27320387[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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