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Dynamic Behavior of Trigger Factor on the Ribosome
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 riboso...
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Published in: | Journal of molecular biology 2016-09, Vol.428 (18), p.3588-3602 |
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Main Authors: | , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | 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.
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•Trigger factor's interaction with NCs on the ribosome is studied.•We have analyzed TF–ribosome–NC complexes via cryo-electron microscopy.•When bound to the ribosome, TF's flexibility depends on the NC length.•The rearranged RBD of TF provides a first landing platform for the NC.•Conformational dynamics of TF on the ribosome are coordinated with NC binding. |
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ISSN: | 0022-2836 1089-8638 |
DOI: | 10.1016/j.jmb.2016.06.007 |