InterPro domain: IPR037041

In the Escherichia coli cytosol, a fraction of the newly synthesised proteins requires the activity of molecular chaperones for folding to the native state. The major chaperones implicated in this folding process are the ribosome-associated Trigger Factor (TF), and the DnaK and GroEL chaperones with their respective co-chaperones. Trigger Factor is an ATP-independent chaperone and displays chaperone and peptidyl-prolyl-cis-trans-isomerase (PPIase) activities in vitro . It is composed of at least three domains, an N-terminal domain which mediates association with the large ribosomal subunit, a central substrate binding and PPIase domain with homology to FKBP proteins, and a C-terminal domain of unknown function. The positioning of TF at the peptide exit channel, together with its ability to interact with nascent chains as short as 57 residues renders TF a prime candidate for being the first chaperone that binds to the nascent polypeptide chains [ 1 ].

This entry represents the C-terminal domain superfamily of bacterial trigger factor proteins, which has a multi-helical structure consisting of an irregular array of long and short helices. This domain is structurally similar to the peptide-binding domain of the bacterial porin chaperone SurA.

This entry also matches foldase protein PrsA N-terminal region. PrsA plays an important role in protein secretion by helping the post-translocational extracellular folding of several secreted proteins [ 2 ].

1. Trigger Factor and DnaK possess overlapping substrate pools and binding specificities. Mol. Microbiol. 47, 1317-28
2. Production of Bacillus anthracis protective antigen is dependent on the extracellular chaperone, PrsA. J Biol Chem 278, 18056-62