Download Mendeley1.3 angstrom Crystal Structure of E. coli Peptidyl-Prolyl Isomerase B with Uniform Substitution of Valine by (2 S ,3 S )-4-Fluorovaline Reveals Structure Conservation and Multiple Staggered Rotamers of CH 2 F Groups.
Frkic, R.L., Tan, Y.J., Maleckis, A., Chilton, N.F., Otting, G., Jackson, C.J.(2024) Biochemistry 63: 2602-2608
- PubMed: 39316701
- DOI: https://doi.org/10.1021/acs.biochem.4c00345
- Primary Citation of Related Structures:
9C5D - PubMed Abstract:
(2 S ,3 S )-4-Fluorovaline (FVal) is an analogue of valine, where a single CH 3 group is substituted by a CH 2 F group. In the absence of valine, E. coli valyl-tRNA synthetase uses FVal as a substitute, enabling the production of proteins uniformly labeled with FVal. Here, we describe the production and analysis of E. coli peptidyl-prolyl isomerase B where all 16 valine residues have been replaced by FVal synthesized with a 13 C-labeled CH 2 F group. Although the melting temperature is lower by about 11 °C relative to the wild-type protein, the three-dimensional protein structure is almost completely conserved, as shown by X-ray crystallography. The CH 2 F groups invariably populate staggered rotamers. Most CH 2 F groups populate two different rotamers. The increased space requirement of fluorine versus hydrogen does not prohibit rotamers that position fluorine next to a backbone carbonyl carbon. 19 F NMR spectra show a signal dispersion over 25 ppm. The most high-field shifted 19 F resonances correlate with large 3 J HF coupling constants, confirming the impact of the γ- gauche effect on the signal dispersion. The present work is the second experimental verification of the effect and extends its validity to fluorovaline. The abundance of valine in proteins and structural conservation with FVal renders this valine analogue attractive for probing proteins by 19 F NMR spectroscopy.
Organizational Affiliation:
ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia.
