Characterization of the structural forces governing the reversibility of the thermal unfolding of the human acidic fibroblast growth factor

Abstract

Human acidic fibroblast growth factor (hFGF1) is an all beta-sheet protein that is involved in the regulation of key cellular processes including cell proliferation and wound healing. hFGF1 is known to aggregate when subjected to thermal unfolding. In this study, we investigate the equilibrium unfolding of hFGF1 using a wide array of biophysical and biochemical techniques. Systematic analyses of the thermal and chemical denaturation data on hFGF1 variants (Q54P, K126N, R136E, K126N/R136E, Q54P/K126N, Q54P/R136E, and Q54P/K126N/R136E) indicate that nullification of charges in the heparin-binding pocket can significantly increase the stability of wtFGF1. Triple variant (Q54P/K126N/R136E) was found to be the most stable of all the hFGF1 variants studied. With the exception of triple variant, thermal unfolding of wtFGF1 and the other variants is irreversible. Thermally unfolded triple variant refolds completely to its biologically native conformation. Microsecond-level molecular dynamic simulations reveal that a network of hydrogen bonds and salt bridges linked to Q54P, K126N, and R136E mutations, are responsible for the high stability and reversibility of thermal unfolding of the triple variant. In our opinion, the findings of the study provide valuable clues for the rational design of a stable hFGF1 variant that exhibits potent wound healing properties.

Structural insights into inhibition of PRRSV Nsp4 revealed by structure-based virtual screening, molecular dynamics, and MM-PBSA studies

“…To better understand the H-bond and its contributions to the overall stability of each system, an H-bond analysis of natural compounds-Nsp4 complexes were calculated. The hydrogen bonding study indicates that all of the Nsp4-complexes are stable and made bonding with essential catalytic residues [ 49 ]. The overall analysis revealed that each complex was stabilizing after 70 ns indicating better interaction with Nsp4 in terms of stability that is required for its inhibition.…”

Pharmacology of Heparin and Related Drugs: An Update

“…It is interesting to note that the thermal stability of FGF-1 is strongly affected by structural changes in and near the heparin binding site. Nullification of charges in the heparin binding pocket by mutagenesis was found to significantly increase the stability of wtFGF-1 (Agrawal et al, 2021), whereas the introduction of a basic residue to extend the heparin binding site (D82R) increased backbone flexibility and reduced biologic activity, in spite of increased affinity for heparin (Davis et al, 2018).…”