Trigger factor (TF) is the first chaperone to interact with nascent chains and facilitate their folding within bacteria.
TF possesses a three-state equilibrium in vivo: monomeric TF bound to ribosome, free monomeric, and dimeric TF in
cytoplasm. TF consists of an N-terminal ribosome binding domain, a middle peptidyl–prolyl cis/trans isomerase (PPIase)
domain and a C-terminal domain involved in substrate binding and dimerization. Investigation of the effect of C-terminal
13 region on TF structure and function will help to further the understanding of its mechanism as a chaperone in vitro and
in vivo. Here we present TF419, a TF mutant from which the C-terminal 13 residues were deleted to investigate the role of
these residues in the structure stability and function of intact molecules. Small angle X-ray scattering (SAXS), fluorescence
measurements and limited proteolysis results suggested that TF transitioned to a compact conformation when the Cterminal
13 residues were truncated. Further biochemical results reveal that TF dimerization was decreased as a result of
the truncation. These results suggested that the C-terminal 13 residues play an important role in structural stability and
chaperone function of TF.
Keywords: C-terminal truncation, dimerization, molecular chaperone, small angle X-ray scattering, trigger factor.
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