Dynamic Behavior of Trigger Factor on the Ribosome

作者：Deeng J; Chan K Y; van der Sluis E O; Berninghausen O; Han W; Gumbart J; Schulten K; Beatrix B; Beckmann R

来源：Journal of Molecular Biology, 2016, 428(18): 3588-3602.

DOI：10.1016/j.jmb.2016.06.007

Trigger 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.

• 出版日期2016-9-11