Osmolyte-Like Stabilizing Effects of Low GdnHCl Concentrations on d-Glucose/d-Galactose-Binding Protein

International Journal of Molecular Sciences. 2017;18(9):2008 DOI 10.3390/ijms18092008

 

Journal Homepage

Journal Title: International Journal of Molecular Sciences

ISSN: 1661-6596 (Print); 1422-0067 (Online)

Publisher: MDPI AG

LCC Subject Category: Science: Biology (General) | Science: Chemistry

Country of publisher: Switzerland

Language of fulltext: English

Full-text formats available: PDF, HTML, XML

 

AUTHORS


Alexander V. Fonin (Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, 194064 St. Petersburg, Russia)

Alexandra D. Golikova (Saint Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia)

Irina A. Zvereva (Saint Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia)

Sabato D’Auria (CNR, Institute of Food Science, via Roma 64, 83100 Avellino, Italy)

Maria Staiano (CNR, Institute of Food Science, via Roma 64, 83100 Avellino, Italy)

Vladimir N. Uversky (Department of Molecular Medicine and Byrd Alzheimer’s Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA)

Irina M. Kuznetsova (Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, 194064 St. Petersburg, Russia)

Konstantin K. Turoverov (Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, 194064 St. Petersburg, Russia)

EDITORIAL INFORMATION

Blind peer review

Editorial Board

Instructions for authors

Time From Submission to Publication: 11 weeks

 

Abstract | Full Text

The ability of d-glucose/d-galactose-binding protein (GGBP) to reversibly interact with its ligands, glucose and galactose, makes this protein an attractive candidate for sensing elements of glucose biosensors. This potential is largely responsible for attracting researchers to study the conformational properties of this protein. Previously, we showed that an increase in the fluorescence intensity of the fluorescent dye 6-bromoacetyl-2-dimetylaminonaphtalene (BADAN) is linked to the holo-form of the GGBP/H152C mutant in solutions containing sub-denaturing concentrations of guanidine hydrochloride (GdnHCl). It was hypothesized that low GdnHCl concentrations might lead to compaction of the protein, thereby facilitating ligand binding. In this work, we utilize BADAN fluorescence spectroscopy, intrinsic protein UV fluorescence spectroscopy, and isothermal titration calorimetry (ITC) to show that the sub-denaturing GdnHCl concentrations possess osmolyte-like stabilizing effects on the structural dynamics, conformational stability, and functional activity of GGBP/H152C and the wild type of this protein (wtGGBP). Our data are consistent with the model where low GdnHCl concentrations promote a shift in the dynamic distribution of the protein molecules toward a conformational ensemble enriched in molecules with a tighter structure and a more closed conformation. This promotes the increase in the configurational complementarity between the protein and glucose molecules that leads to the increase in glucose affinity in both GGBP/H152C and wtGGBP.