Probing conformational transitions of PIN1 from L. major during chemical and thermal denaturation.

Probing conformational transitions of PIN1 from L. major during chemical and thermal denaturation. Int J Biol Macromol. 2020 Mar 21;: Authors: Biswas G, Ghosh S, Raghuraman H, Banerjee R Abstract PIN1 proteins are a class of peptidyl prolyl cis-trans isomerases (PPIases), which have been implicated in numerous cellular functions like cell cycle progression, transcriptional control, signal transduction, promotion of oncogenesis and host-parasite interactions. In this work, the unfolding mechanism of a single domain PIN1 from Leishmania major (LmPIN1) has been characterized during thermal and denaturant-induced unfolding by differential scanning calorimetry (DSC), fluorescence and circular dichroism. Further, MD simulations have been performed to structurally probe the possible stages of its unfolding process. Both the fluorescence and CD data confirm classical two-state unfolding transitions for urea and GdnHCl. The thermal unfolding of LmPIN1, characterized by DSC, could optimally be fitted to a non-two-state transition curve exhibiting two Tm's (53 °C and 57 °C) suggesting the possibility of an intermediate. Thermal unfolding of the modeled LmPIN1 by MD simulation shows that the unfolding process is initiated by increased fluctuations (dynamics) spanning residues 70-80, followed by perturbations in the sheet system and disjuncture of helix-sheet packing. Importantly, simulation and fluorescence quenching studies clearly sugges...
Source: International Journal of Biological Macromolecules - Category: Biochemistry Authors: Tags: Int J Biol Macromol Source Type: research