title: SAXS data based global shape analysis of trigger factor (TF) proteins from E. coli, V. cholerae, and P. frigidicola: resolving the debate on the nature of monomeric and dimeric forms.
abstract: Dimerization of bacterial chaperone trigger factor (TF) is an inherent protein concentration based property which available biophysical characterization and crystal structures have kept debatable. We acquired small-angle X-ray scattering (SAXS) intensity data from different TF homologues from Escherichia coli (ECTF), Vibrio cholerae (VCTF), and Psychrobacter frigidicola (PFTF) while varying each protein concentration. We found that ECTF and VCTF adopt a compact dimeric shape at higher concentrations which did not resemble the "back-to-back" conformation reported earlier for ECTF from crystallography (PDB ID: 1W26 ). In contrast, PFTF remained monomeric throughout the concentration range 2-90 μM displaying a multimodal open extended conformation. OLIGOMER analysis showed that both the ECTF and VCTF remained completely monomeric at lower concentrations (2-11 μM), while, at higher concentrations (60-90 μM), they adopted a dimeric form. Interestingly, the equilibrium existed in the medium concentration range (>11 and <60 μM), which correlates with the physiological concentration (40-50 μM) of TF in cell cytoplasm. Additionally, circular dichroism data revealed that solution structures of ECTF and VCTF contain predominantly α-helical content, while PFTF contains 310-helical content.
authors.affiliation: CSIR-Institute of Microbial Technology, Chandigarh, India.
authors.forename: Yogendra S
authors.initials: YS
authors.lastname: Rathore
authors.affiliation: CSIR-Institute of Microbial Technology, Chandigarh, India.
authors.forename: Reema R
authors.initials: RR
authors.lastname: Dhoke
authors.affiliation: CSIR-Institute of Microbial Technology, Chandigarh, India.
authors.forename: Maulik
authors.initials: M
authors.lastname: Badmalia
authors.affiliation: CSIR-Institute of Microbial Technology, Chandigarh, India.
authors.forename: Amin
authors.initials: A
authors.lastname: Sagar
authors.affiliation: CSIR-Institute of Microbial Technology, Chandigarh, India.
authors.lastname: Ashish
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase / Q000737:chemistry*; D011487:Protein Conformation; D055503:Protein Multimerization; D044096:Psychrobacter / Q000737:chemistry*; D053838:Scattering, Small Angle; D016415:Sequence Alignment; D014734:Vibrio cholerae / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C403324:trigger factor, E coli; D019696:Peptidylprolyl Isomerase