Aromatic Cluster Sensor of Protein Folding: Near-UV Electronic Circular Dichroism Bands Assigned to Fold Compactness.

Publisher: Wiley-VCH Country of Publication: Germany NLM ID: 9513783 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1521-3765 (Electronic) Linking ISSN: 09476539 NLM ISO Abbreviation: Chemistry Subsets: MEDLINE

Original Publication: Weinheim, Germany : Wiley-VCH

Protein Folding*; Circular Dichroism/*methods ; Proteins/*chemistry ; Tryptophan/*chemistry ; Tyrosine/*chemistry; Amino Acid Sequence ; Electrons ; Models, Molecular ; Protein Conformation ; Protein Stability ; Temperature

Both far- and near-UV electronic circular dichroism (ECD) spectra have bands sensitive to thermal unfolding of Trp and Tyr residues containing proteins. Beside spectral changes at 222 nm reporting secondary structural variations (far-UV range), L b bands (near-UV range) are applicable as 3D-fold sensors of protein's core structure. In this study we show that both L b (Tyr) and L b (Trp) ECD bands could be used as sensors of fold compactness. ECD is a relative method and thus requires NMR referencing and cross-validation, also provided here. The ensemble of 204 ECD spectra of Trp-cage miniproteins is analysed as a training set for "calibrating" Trp↔Tyr folded systems of known NMR structure. While in the far-UV ECD spectra changes are linear as a function of the temperature, near-UV ECD data indicate a non-linear and thus, cooperative unfolding mechanism of these proteins. Ensemble of ECD spectra deconvoluted gives both conformational weights and insight to a protein folding↔unfolding mechanism. We found that the L b ²⁹³ band is reporting on the 3D-structure compactness. In addition, the pure near-UV ECD spectrum of the unfolded state is described here for the first time. Thus, ECD folding information now validated can be applied with confidence in a large thermal window (5≤T≤85 °C) compared to NMR for studying the unfolding of Trp↔Tyr residue pairs. In conclusion, folding propensities of important proteins (RNA polymerase II, ubiquitin protein ligase, tryptase-inhibitor etc.) can now be analysed with higher confidence.
(© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Keywords: Electronic circular dichroism spectra; Trp-Tyr interacting residues; folding intermediates; sensors; thermal unfolding

0 (Proteins)
42HK56048U (Tyrosine)
8DUH1N11BX (Tryptophan)

Date Created: 20160810 Date Completed: 20180130 Latest Revision: 20180130

20250114

10.1002/chem.201602455

27504963