Structure of the E. coli trigger factor bound to a translating ribosome
[RL29_ECOLI] Binds 23S rRNA. It is not essential for growth.[HAMAP-Rule:MF_00374] One of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit. Contacts trigger factor (PubMed:12226666).[HAMAP-Rule:MF_00374] [TIG_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.   [RL24_ECOLI] One of two assembly initiator proteins, it binds directly to the 5'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit. It is not thought to be involved in the functions of the mature 50S subunit in vitro. One of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit. [RL23_ECOL5] One of the early assembly proteins it binds 23S rRNA. One of the proteins that surrounds the polypeptide exit tunnel on the outside of the ribosome. Forms the main docking site for trigger factor binding to the ribosome (By similarity).
Publication Abstract from PubMed
Ribosome-associated chaperone Trigger Factor (TF) initiates folding of newly synthesized proteins in bacteria. Here, we pinpoint by site-specific crosslinking the sequence of molecular interactions of Escherichia coli TF and nascent chains during translation. Furthermore, we provide the first full-length structure of TF associated with ribosome-nascent chain complexes by using cryo-electron microscopy. In its active state, TF arches over the ribosomal exit tunnel accepting nascent chains in a protective void. The growing nascent chain initially follows a predefined path through the entire interior of TF in an unfolded conformation, and even after folding into a domain it remains accommodated inside the protective cavity of ribosome-bound TF. The adaptability to accept nascent chains of different length and folding states may explain how TF is able to assist co-translational folding of all kinds of nascent polypeptides during ongoing synthesis. Moreover, we suggest a model of how TF's chaperoning function can be coordinated with the co-translational processing and membrane targeting of nascent polypeptides by other ribosome-associated factors.
Molecular mechanism and structure of Trigger Factor bound to the translating ribosome.,Merz F, Boehringer D, Schaffitzel C, Preissler S, Hoffmann A, Maier T, Rutkowska A, Lozza J, Ban N, Bukau B, Deuerling E EMBO J. 2008 Jun 4;27(11):1622-32. Epub 2008 May 22. PMID:18497744
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.